PDA

View Full Version : Boiler and thermostat conundrum.


SpringHeeledJack
5th Jan 2013, 13:13
Gentlemen.....A friend has bought a property recently and all is fine and dandy, but it would appear that there is NO thermostat to be found anywhere. Having checked this meself it would appear to be so, not on any wall/crevice/corner high or low. The effect seems to be that when th central heating is on, the boiler is never 'resting' as a desired anbient temperature is never attained. Perfect when utility bills are heading skywards :ouch:

So the question is has anyone managed to purchase a wireless thermostat that can be somehow joined with the boiler without too much complication ? The boiler is about 7 years old so it's not a dinosaur. Any ideas ?



SHJ

arcniz
5th Jan 2013, 13:22
Is "wireless" the most important criterion?

One has found -- over a lot of practice -- that wired connections are intrinsically more consistent, precise, and reliable than wireless ones... because the vast and uncontrollable source of error (aka wireless) is not present.

Wireless is a convenience for installation, perhaps, but how many times does one install the thing -- for how many years service?

Consider theories of how to troubleshoot temperature regulation problems when the wireless path becomes an acolyte of some nearby radio station and begins to operate entirely randomly.

Not saying it cannot be made to work, but simply that you do not want to know the price tag for installing a long-term of use wireless path that equals a cheap piece of wire in performance.

G-CPTN
5th Jan 2013, 13:23
My heating is controlled by a Drayton Digistat RF2 (http://www.draytoncontrols.co.uk/Digistat2RFProgrammableRoomThermostatWireless.aspx) wireless thermostat.

It seems to work . . .

arcniz
5th Jan 2013, 13:29
And so it may.... right up to the moment when...

One knows you are sophisticated in such matters, CPTN, and likely have the insight and experience to discover failure modes and diagnose the mechanisms involved.

That is relatively rare, I have observed, in the general population and in most of the trades.

UniFoxOs
5th Jan 2013, 13:33
My boiler (oil-fired) is simply powered on and off by the thermostat, so it interrupts the live mains connection. Thus it can be fitted anywhere within the circuit - if your mate can do this it's possible the mains feed passes somewhere near where a thermostat can be mounted.

Most boilers have a thermostat inside them monitoring the temperature of the water jacket.

Of course - if the desired temp is never attained you don't need a thermostat, and the boiler is too small for the job.

UFO

G-CPTN
5th Jan 2013, 13:43
Presumably the radiators are all fitted with thermostatic valves? There is an argument that with thermostatic radiator valves, the room thermostat becomes redundant.

My thermostat incorporates a timer, and different ambients can be set thus permitting lower temperatures at night or when the property is unoccupied (whilst still keeping the heating 'on'). There is also a frost thermostat within the boiler which over-rides the room thermostat.

goudie
5th Jan 2013, 13:53
I've had individual radiator thermostats for years but they keep sticking and it's a nuisance having to go round adjusting them so, coincidentally, on Monday, the plumber is coming to fit a wireless thermostat in the lounge. A friend has one and assures me it's a great improvement

Dushan
5th Jan 2013, 14:34
This boiler you are talking about, presumably heats water that is then distributed through radiators to heat the house. Correct?

How is the boiler heated (electricity, gas, oil, nuclear)? How is the water circulated? There should be an electric circulating pump.

This kind of system is supposed to heat the water in the boiler to a pre set temperature, not desired room temperature, but a lot higher, usually around 55C. Once that temperature is reached the circulating pump would start. Once the room temperature is reached the boiler is shut off, but the pump keeps going as the water is still hot. Then, when the water cools down to a set temperature the pump stops. The cycle starts again when the room temperature drops below setting.

So this is a lot more complicated than just a simple thermostat. Furthermore depending on the source of heat the thermostat may be controlling supply of electricity, gas, or oil. The pump/boiler settings are usually done on a secondary thermostat close to the boiler which is actually controlled by the main thermostat in the house. As stated earlier the wireless option, if it exists, is probably not the best solution since it can either stay on or off until re-set. Thermostats, these days, are fairly sophisticated. They have digital displays, can be programmed to set different temperatures during the day and even different days of the week. The main distinction is whether they operate on low voltage (12/24 VDC) or high (110/220 VAC).

You may want to bring in an HVAC guy to have a look and he may either find the "hidden" thermostat or advise you what needs to be done.

Loose rivets
5th Jan 2013, 14:56
Primary thermostat controls the boiler. (probably contained within its casing) This is also the first-line control of the temperature in the cylinder, but in addition to this, there could/should be a stat controlling a motorized valve for the water circuit to the 'coil' in the cylinder.


A house without a stat is daft. Rented one a year ago. Total mystery to me. As said above, walking round banging rad stats to free them is an odd hobby.

Stat controls a motorized valve. When that has run open, it hits a micro-switch which runs the heating circulation pump.

The actual water temperature is only controlled by the primary stat.


I divided my house up into zones. 3 of 'em. Saved a lot of dosh. When finally I found my 'semi siblings' aged 60ish, I was astonished to find two of them did their own plumbing - and one had zoned his house. Must be in the genes.

M.Mouse
5th Jan 2013, 15:09
Many years ago I used to wire central heating systems for numerous heating companies, probably on average around ten per week.

It is IMPOSSIBLE to give satisfactory advice without knowing exactly how the system mentioned by the OP is configured.

Some of what is written above is completely wrong, most of it is accurate FOR SPECIFIC systems, but there is NO generic, one size fits all answer. One small example; a boiler may have a pump overrun requirement where when heat is no longer demanded the pump will continue running to cool the boiler until a pre-determined temperature is reached and it is safe for the water circulation to be halted. If it has that requirement and the water circulation is prematurely interrupted by a room thermostat then damage will result in the long term.

radeng
5th Jan 2013, 16:48
G-CPTN

Your system is fine - until you get a local transmitter in the band, running quite legally anything from 5 watts to 500,000 watts radiated power as against your maximum 10mW. Legally, under EU law (the Short Range Device Decision), these are short range devices which must not cause interference and must accept interference. 433 MHz has become a 'junk band' for SRD, just like 2.4 GHz.

It's meetings on regulations and so-on for SRD that has me in Dublin all next week...........Still, at least I should be able to get decent glass of Guinness.

So if there's any chance of the communications being critical, DON'T use wireless. It's because of the 'junk' nature of SRD bands that medical implants share frequencies with Meteorological balloons and the Earth Exploration Satellite Service, which means that interference from those sources is low.

lgweng
5th Jan 2013, 17:45
As was stated earlier, the boiler supply passes through the immersion tank and then the radiators are controlled by thermostatic rad valves. If a room feels cold,turn up the trv. There is no need for a single control thermostat. We have had this system for 10 years now and have found it to work well and efficiently. I did look into fitting a wireless system 'stat a few years ago but decided it was pointless.

Checkboard
5th Jan 2013, 17:51
This one is sexy :)

Nest Smart Thermostat - Home Gadget of the Year | T3 Gadget Awards 2012 (http://awards.t3.com/categories/home-gadget-of-the-year/nest-smart-thermostat)

gingernut
5th Jan 2013, 18:37
Switch it off at the main's and get some of these... http://img.photobucket.com/albums/v617/gingernut123/DSC_0016-2.jpg

ShyTorque
5th Jan 2013, 18:56
But you get tired of logging on each time.

We live in a bungalow and have fitted a combi/condensing boiler in the loft space. It uses a wireless thermostat fitted on the wall below, in the corridor to the bathroom and bedrooms.

Rather than being a plain vanilla thermostat it has about half a dozen "time zones" each with an individually programmable target temperature. You can also programme it to be different every day, or be different just at weekends, if desired. You can also set it to "frost protection" if you're going out for a few days.

No problems at all with it. I think I've only had to change the batteries (2xAA) two or three times in over five years.

Keef
5th Jan 2013, 19:26
Get a real man in!

There should be a thermostat somewhere (he said, based on advice from our plumber) - preferably in the hall. The radiator in that place should NOT have a thermostatic valve. That is the one that gives the circulating pump something to work against.

In our Norfolk hideout, the thermostat is out in the boiler house - a separate building. The theory is that it will detect freezing temperatures and turn the heating on. It seems to work.

Avoid wireless ones if at all possible. There are too many other things squirting stuff into the radio spectrum to be sure of a problem-free life.

OFSO
5th Jan 2013, 19:49
that there is NO thermostat to be found

I bet there is ! My gas central heating has a thermostat fitted on the return water pipe and when the heating is on this controls the cycling of the heating. However since I have a second thermostat in the living room, the one on the water pipe is set to full on......

Thread Drift: it is ten p.m. here in Catalunia and the outside temperature is 21c. I have NEVER known such high January temperatures in the 20 years I have lived here - needless to say we have neither the woodstove lit nor the heating on.

gingernut
5th Jan 2013, 19:59
bit of drift here, but got one of these power monitor's from the power company...went round the house, turned out all of the not wanted lights and things on standby, reduced the rate from 0.10 an hour to 0.05. Did the maths over a year and tripped over the dog.

Loose rivets
5th Jan 2013, 20:23
It's 10c outside and 22 in my den. I have a huge sweater on and am constantly chilly.

It's true about the need to tailor the system to a specific installation. Mine was a hotch-potch built up over years. A 60 quid boiler from the local rag was the heart of the house, beautifully built bit of kit. To sell the house I put a new Potterton in. It was not all that much more economical and really struggled to heat all the zones at once.

I just can't imagine what happens to those weird new systems when all rad valves close. A stat on the inlet? Seems so counter-intuitive as a design. Just a miserable bit of rubbish in a cupboard that let cold water to the kitchen tap after a very few moments of being off. I'd invested so much in the past getting instant hot on a double pipe system. Very frustrating.



Seeing those logs makes me think of my home in Frinton. I used to have a store of them out back, and when they were about a year old they'd come into the boiler-house for a week or so. But still they'd go off with a heck of a bang sometimes.

A quality carpet was a good investment. Used to rush to the origin of the smoke, grab the bit and damp the floor. For 25 years you'd hardly see the marks due to the classical pattern.

I'm dreading living at home in the winter.

G-CPTN
5th Jan 2013, 20:40
I'm dreading living at home in the winter.
'Thermals' (long johns) and multiple sweaters (and a woollen hat) and two pairs of socks to keep your feet from freezing can make life more bearable.

fireflybob
5th Jan 2013, 21:03
Have had a wireless room thermostat for circa five years and it has functioned faultlessly.

One advantage of a wireless thermostat is that you can move it from room to room as desired.

As it is a thermistor it also controls temperature to the nearest 0.5 deg c as opposed to the basic thermostats which operate +/- circa 2 deg c of selected temperature.

When I moved into my house I took all the beastly radiator thermostats out which I think are more trouble than they are worth!

gingernut
5th Jan 2013, 21:05
Couldn't agree more LR.

How Mrs G likes the porch..... http://img.photobucket.com/albums/v617/gingernut123/DSCN8163.jpg

How I like the porch... http://img.photobucket.com/albums/v617/gingernut123/DSC_0026.jpg

gingernut
5th Jan 2013, 21:08
"Put them under the shed," she says.

"But the shed's full," I reply.

http://img.photobucket.com/albums/v617/gingernut123/DSC_0022-3.jpg

gingernut
5th Jan 2013, 21:10
"The log shed?" .......

http://img.photobucket.com/albums/v617/gingernut123/DSC_0006-2.jpg

AlpineSkier
5th Jan 2013, 22:54
Loose Rivets
Do you have a regular routine Texas/Frinton ?

Loose rivets
6th Jan 2013, 04:33
Ah, would that I could. 'twas the plan, but like many plans, actuality intervened.

One wishes to turn back the clock and try again.


'Thermals' (long johns) and multiple sweaters (and a woollen hat) and two pairs of socks to keep your feet from freezing can make life more bearable.

I did that in 2011, but people in the pub laughed at me. Well, it was only September. The terrible thing is, I'm not kidding.

SpringHeeledJack
6th Jan 2013, 07:27
Thanks for the ideas chaps. The system in question is a gas fired combination boiler (Worcester Junior) in the UK, no immersion tank, 11 radiators each with a normal control on the side (1-5) for controlling how hot, but despite all efforts no wall mounted thermostat control to be found anywhere, even when the property was empty....It seems that the system might have been installed by a mate of the previous owner and they omitted to put said thermostat in, obviously in the days before it became law to only use a Corgi registered plumber. They will have to get a plumber in, as simple as that.

A few years back I had a wireless thermostat, although it came new with the heating system and it seemed very user friendly, but my question was if these devices could be easily retrospectively connected to a system and if anyone had done it :8


SHJ

Loose rivets
6th Jan 2013, 08:31
But what would you cause it to switch?

hellsbrink
6th Jan 2013, 08:32
Room thermostats are an old fashioned way of doing things. The boiler has a thermostat to prevent it heating unnecessarily and each individual radiator has it's own thermostat so you can control the temperature in each room instead of all the heating being controlled by the temperature you wish in one, usually the living, room.

Far more efficient, as you can make sure the heat only goes to where you actually need it instead of everywhere at the same level at the same time. Once these temperatures are achieved, the thermostat on the boiler shuts the boiler down and the leccy used by the pump during the time the boiler is not heating is of no consequence in the long term.

No need for a plumber, your friend's system is more efficient and effective than one with a single thermostat controlling the temperature in only one room.

He should be glad.

mike-wsm
6th Jan 2013, 08:34
Jack - those 'normal controls' are the thermostats. :p

M.Mouse
6th Jan 2013, 10:34
When I fitted radiator thermostatic valves, I put a bypass valve between the pump delivery and the return to the boiler.

Just one of the many situations where a by-pass of some description is essential. With TRVs the other alternative is to leave one radiator permanently on with no TRV.

Grayfly
6th Jan 2013, 10:39
As the last few posts have pointed out, a thermostatic rad valve is the controller for each radiator. No need for a room stat. Each room can be controlled at the temperature you want for that room by setting from frost control to maximum, usually between 5c and 23C depending on your boiler temperture setting. A wall mounted stat would just control all the rooms at the same temperature you set on the wall stat.

The boiler stat will control the circulating water temperature, so when that's satisfied the boiler will shut down and start again when the circulating water temperature drops.

Keef
6th Jan 2013, 11:04
Yes, but you MUST have a path for the pumped water to go when all the rad stats have turned off because it's hot enough in the rooms. Otherwise, the pump is pushing against a solid block, which is not good for it.

The conventional way to do that is to have one room with a thermostat which turns off the pump. In most cases, that's the coldest place in the house (usually the hall) so by the time that switches off, the rooms are all warm. Works for me.

Grayfly
6th Jan 2013, 11:26
As has been said before, a bypass sorts all that out without the need to switch off pumps etc. Works for me:)

M.Mouse
6th Jan 2013, 12:16
The pump is an induction motor with a free spinning impeller and can run with no detrimental effect whether water is flowing or not although it might sound quite noisy. The issue is that if the heating system is on and ALL TRVs are at temperature and close then with no water circulation the boiler will heat its internal, non-flowing, water and its own thermostat will rapidly reach temperature and turn off. After a period of cooling the boiler thermostat will call for heat and the boil will fire again and rapidly heat up until the boiler thermostat turns off again i.e. the boiler will experience rapid and short cycles. Some boilers will survive but low water content boilers can be permanently damaged.

If it is an open vented system you can even get circulation through teh expansion pipe into the header tank and back through the system. Quite entertaining to find a cold loft space filling with steam.

As I mentioned earlier there are many, many different types of system and variations on a theme. Over the years I have seen some truly extraordinary systems installed or altered by people with little or no knowledge. Most are inefficient or just don't work properly. The most dangerous I ever came across was a Baxi back boiler on a system which some bozo had fitted a 'Pri-matic' cylinder which was expressly forbidden in Baxi's installation literature. The result being that the gravity primaries had furred up. We were called in when the new house owners were concerned at the noise the boiler was making. The noise was the boiler jumping on its stand as the water in the furred up heat exchanger was heating and expanding with insufficient means of escape. The owners were quite upset when we explained and capped of the gas to prevent an explosion!

My experience was in the 15+ years before I started flying commercially. At that time I worked for a CORGI registered firm. I still do a little heating work now but am not gas safe registered so utilise the services a friend of mine who is registered and up to date on the latest system technology.

reynoldsno1
6th Jan 2013, 21:33
Recently had a new hot water tank installed - mains pressure, ceramic contained in its own insulated container - & no thermostat. It is inbuilt at about 60C and cannot be adjusted. An external tempering valve mixes the hot & cold water to the required temp ...

SpringHeeledJack
7th Jan 2013, 17:56
Thanks once again for advice chaps. A question, (and one I feel a bit sheepish asking), the control valve on your atypical radiator with 1-5 in Roman numerals and *, controls the amount of the hot water into the radiator doesn't it ? This made me see it not as a thermostat, although it does control the thermal output of said radiator. I have seen over the years some thermostat controls on radiators, but attatched to a bleed valve on one of the upper portions.

The person to whom this system belongs complained that the boiler was burning gas almost continuously, somehow never shutting off and this was concerning them especially with the ever higher gas prices and assumed it was due to the required ambient temp never being reached. Perhaps they leave windows open :p



SHJ

G-CPTN
7th Jan 2013, 18:07
It's easy enough to purchase a thermometer and check the individual rooms to see whether the temperature plateaus at a particular figure (and whether that is comfortable or excessive).

Of course if the boiler output is inadequate then it will be running constantly.

threepeanutpax
7th Jan 2013, 18:12
System should have a room thermostat to comply with part L of building regs (energy efficiancy)
Digistats work well I use them over hard wired when installing a system and clients like them.

OFSO
7th Jan 2013, 18:18
The radiator in Mrs OFSO's studio fell off the wall this afternoon, it's cast iron and both of us can't shift it. Tried jacking it up with a pair of car jacks but no way can get back into place so it's sitting on a couple of logs intended for the woodstove.

Winter fuel allowance won't cover this repair.

G-CPTN
7th Jan 2013, 18:51
The radiator in Mrs OFSO's studio fell off the wall this afternoon,
Are you using heavy water (http://en.wikipedia.org/wiki/Heavy_water)?

OFSO
7th Jan 2013, 18:57
No....it fell off as a result of being used for a non-heating activity (!)

M.Mouse
7th Jan 2013, 19:08
A question, (and one I feel a bit sheepish asking), the control valve on your atypical radiator with 1-5 in Roman numerals and *, controls the amount of the hot water into the radiator doesn't it ?

The only question you should feel sheepish about is the one you don't ask! I, and I think most people who contribute to these threads, never mind explaining something that I understand which someone else doesn't. The danger of course is that sometimes the people replying clearly don't understand the subject either!

You are almost correct the Thermostatic Radiator Valve you describe reduces or increases the FLOW of hot water through the radiator depending on the room temperature it senses.

This made me see it not as a thermostat, although it does control the thermal output of said radiator. I have seen over the years some thermostat controls on radiators, but attatched to a bleed valve on one of the upper portions. There have been many variants over the years with some having remote sensing and connected to teh valve by a copper capillary tube.

The person to whom this system belongs complained that the boiler was burning gas almost continuously, somehow never shutting off and this was concerning them especially with the ever higher gas prices and assumed it was due to the required ambient temp never being reached. Perhaps they leave windows open.

If I had recently bought a property and didn't have the knowledge to make a fair assessment of whether my system was working properly or not I would be very inclined to pay for someone to come and give the system a once over. Like cars boilers do need occasional servicing anyway!

System should have a room thermostat to comply with part L of building regs (energy efficiency)

That is correct and one of the more baffling building regulations given how coarse the control is which a basic room thermostat provides.

ShyTorque
7th Jan 2013, 19:21
No....it fell off as a result of being used for a non-heating activity (!)

Ooer! If you carry on doing that you might not need the radiator.....

Loose rivets
7th Jan 2013, 19:23
I dunno, it all seems so counter-intuitive. Gut feelings, and all that.


i.e. the boiler will experience rapid and short cycles. Some boilers will survive but low water content boilers can be permanently damaged.


I was sort of imagining that before I read it.


In the homes I've borrowed or rented since selling mine, there have been perhaps 60 rad-stat valves. About 10% of them worked.

In the last flat I gave up on one vital one. I got a small spanner and used the limiter on the other end. That worked fine.

Would exercising them help I wonder. Also, is there a water additive that would stop furring up and perhaps lube such devices?

spekesoftly
7th Jan 2013, 20:25
I find the problem of sticking TRVs (Danfoss in my property) is considerably reduced by leaving the valves fully open when the central heating system is not required. If the valve pin sticks in the open position it will usually release under the pressure of closing the valve. Pins that stick in the closed position normally require removal of the TRV head before they can be freed.

Rossian
7th Jan 2013, 20:38
....the plumber on my resettlement course at Catterick was very rude about TRVs. His solution was to give them a "gentle clatter" on the end with a rubber faced hammer which achieves the end of freeing any stuck "furred-up" pins.

He declined a more precise definition of a "gentle clatter", but said it needed doing once or twice a year.


The Ancient Mariner

Keef
7th Jan 2013, 22:18
I'm fortunate in living in a village with a resident plumber who is outstanding.
He supervised the builders doing our repair work, and wouldn't let them do anything with the heating system. When it was refilled, he made sure enough inhibitor was added.

There are thermostatic valves in every room except the hall, and they all work as they should.

It's a good tip to open them wide come the summer when the heating gets turned off.

M.Mouse
7th Jan 2013, 22:36
In the last flat I gave up on one vital one. I got a small spanner and used the limiter on the other end. That worked fine.

The valve to which you refer is generally called the lockshield valve and is used to balance the system and rarely needs adjusting once the system is installed, balanced and running properly unless alterations or additions to the heating circuit are made.

To explain balancing the system for anybody who is interested or unaware take an example of say a large 4 bedroom bungalow with a boiler situated at one end. If all the valves on each end of every radiator were left fully open and the central heating fired up the pump would start pumping water around the heating circuit. Basic physics will mean that the water circulation would take the path of least resistance i.e. the majority of the flow would be through the nearest radiator with the next nearest receiving some flow and so on but with a large system the radiators furthest away would remain stone cold. By closing down the lockshield valves on the radiators nearest the boiler and progressively opening the others the further you are away from the boiler the resistance to flow through each radiator becomes more equal (balanced) and all radiators should get hot equally.

There is a bit more to it than that but that is the basic idea.

The tip about leaving TRVs fully open when the heating is not needed is a good tip. I have them throughout my house and they work brilliantly.

Loose rivets
8th Jan 2013, 07:11
and rarely needs adjusting once the system is installed,

Quite so . . . IF the valve at the other end is working. Mine wasn't, and I was turning pink.


I used to go around the house throttling the . . . Oooo, never knew they were called Lockshield . . . but tightening those thingies to the minimum heat I could usefully accept.

I expect there's a technical way of doing it, but other than using a stethoscope, I can't think of one.

Our pump really had to work hard. There were 15 rads, some of them very long, and it became a heck of a juggling trick to balance them all. Zoning really did help lessen the peak flow times. It was just chance, but often one would be on without the others.

Lightning Mate
8th Jan 2013, 09:00
It's a good tip to open them wide come the summer when the heating gets turned
off.

Sound advice, even with non-thermostatic valves.

I drain down every two years and use more than the recommended Fernox.

All my radiators have thermostatic valves and I have had no problems with any of them over the last fifteen years.

Loose rivets
8th Jan 2013, 16:18
How is the rad water supplied in a modern/condenser system?

By that I mean is there a tank or PRV keeping it supplied? Obviously it has to be separate from the tap water.


I drain down every two years and use more than the recommended Fernox.


This has bought back a memory. An old school contemporary, a lifetime plumber, reacted to the name Fernox. Much sucking of teeth and shaking of head. I eventually pried the reason out of him. Only one word, mind. 'Leaks'.

I seemed he liked the build-up and calcium to seal the joints and pinpricks.

I only called him in when my company got so demanding I hadn't got time to play. He did overcome one of my difficulties: A socking great 1 1/4" Presstex T junction that I could not move cos the pipe went through holes in the joists. A few minutes later I was back and he'd done it. I can only conclude he cut the pipe to the shortest possible length to go into the olive. It didn't leak so I accepted it. I'll never know.




.

cockney steve
8th Jan 2013, 23:23
Further to the Lockshield issue... (incidentally, name derives from the cover which shields the spindle and therefore locks it, the ones with the twiddly knob on, are exactly the same, a tap! )

I was taught that a conventional boiler worked most efficiently with the internal 'stat set at i70 *f

fire up boiler when all valves and lockshields are fully open. start at Rad, nearest the boiler and screw down lockshield until there's a stable 10* F difference between "in" and "out" ends of radiator repeat until all rads have a 10* drop across them. refit lockshields, control each rad by the valve.
I don't understand the comments about "opening" thermostatic valves.

like a car-thermostat, if they're set to a temperature higher than ambient, they will be open anyway.....when the rad heats the room to the desired "set" temp, the 'stat will close the valve, slowing or stopping circulation until the room drops below "set" temp, when it will open the valve to heat the rad again. of course, if the heating's off, the valve may well be open but the rad won't heat, though water will be free to heat it as soon as the heating switches on.

I have yet to be convinced that these pressurised Condensing-boilers, with their attendant problems of leaks and a shortish service-life, will recoup their outlay in saved fuel-costs.

Friend recently had to have a new "brain" in a 2-year old boiler....400 buys a lot of "extra" gas for the old, less efficient boiler!

spekesoftly
9th Jan 2013, 00:27
I don't understand the comments about "opening" thermostatic valves.

......................................... .......................................... ...........................
The tip about leaving the TRVs fully open ONLY applies when the central heating system is not being used for a prolonged period (ie - in the summer when the CHG will nornally remain switched off for several months). During this period of inactivity some TRV gland seal pins have a tendency to stick, rendering the TRV inop when next the heating system is fired up. However, a pin stuck in the fully open position can usually be released by simply closing the valve. If the TRV is left closed during the summer months, and the pin sticks in the closed position, the TRV head will often have to be removed before the seized pin can be freed.

M.Mouse
9th Jan 2013, 11:01
How is the rad water supplied in a modern/condenser system?

Two basic types of heating system irrespective of the type of boiler fitted.

First is open vented which has a small 'header' tank usually located in the roof and with an expansion pipe from the system which rises a few feet above the tank and discharges into said tank when the system water expands.

Second is an unvented (closed) system which is filled and pressurised via a filling loop connected directly to the cold main and fitted with isolating valves. This type of system will also have a pressure vessel which is a large bulbous affair inside of which there is a diaphragm dividing it in half. One side fills with water from the system and the other side is pre-pressurised air. The device is there to accommodate water expansion.

Windy Militant
9th Jan 2013, 12:12
He declined a more precise definition of a "gentle clatter", but said it needed doing once or twice a year.
Tee Hee reminds me of the days I spent seconded to help the pipefitters here at the lab.
We quite frequently used a small plastic mallet to provide said clatter, the technique is somewhat akin to a stun shot in snooker. This is fine if you've done your time and know how to pull the blow to shock the valve and not follow through. Unlike the neddy in admin who hit the valve in his office with a ballpein hammer he'd just requisitioned from stores. Amazing how little force is needed to completely snap the brass body of the valve. :ugh:
Still it meant that once the panic was over and the system refilled we got to spend the rest of the week crawling round under the desks to get at the bleed nipples on the radiators. At least thats what we told the admin girlies we were doing. :E

Oh and be careful playing with lockshields, at that time the lab used to buy cheap valves that used carbon packing on the valve stems. this worked fine when new but used to stick to the stem and if after a while you tried to adjust the lockshield it would break up and leak, in some cases quite badly.

Loose rivets
9th Jan 2013, 12:32
Uses to do all mine with hessian and old fashioned water-pump grease. But then, one was obsessed with plumbing.

M.Mouse
9th Jan 2013, 13:28
Uses to do all mine with hessian and old fashioned water-pump grease.

Funny old thing but I never seem to get a leak using hemp and paste on a joint but often do with PTFE tape. I never seem to put enough PTFE tape on the thread, it seems counter-intuitive given that putting too much hemp on a joint would lock it solid in a few turns!