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Central heating controls

My wife likes the hall temperature to be something like the palm house at Kew Gardens so that it’s ‘nice and warm when we come in’, as I recall the hall rad was refusing to heat up last winter but as it was mild I got away with it, I feel a big job coming on soon!!
 
Its also worth mentioning that boilers (especially condensing) like low return temps in order to work efficiently.

So lots of TRV's might end up costing you rather than saving.
 
Return temp is only a major concern with a condensing boiler - having read how they work on Wiki, I now understand what seems to be referred to as dew point in heating/plumbing trade - actually the return temperature, which does the condensing, for some reason decided to be optimised for 55C.
If your pipes are well lagged and/or within the living space, so that what little heat is lost, is lost to advantage to space heating, within reason, return temperature matters very little.
 
Return temp is only a major concern with a condensing boiler - having read how they work on Wiki, I now understand what seems to be referred to as dew point in heating/plumbing trade - actually the return temperature, which does the condensing, for some reason decided to be optimised for 55C.
If your pipes are well lagged and/or within the living space, so that what little heat is lost, is lost to advantage to space heating, within reason, return temperature matters very little.

Nope it's simple physics, natural gas when burnt condenses or turns to water at 54 degrees C that temperature enables the boiler to recover more useful heat from the boiler flue gasses so when the return water temperature is at that temperature the boiler is able to work at it's most efficient however the result of that temp on the rads is that they are barely warm.
 
Sorry twotone, you may be a great plumber, but you are a VERY long way out on VERY simple physics.

Nope it's simple physics, natural gas when burnt condenses or turns to water at 54 degrees C ………………....

Complete, total, absolute and utter nonsense.

Natural gas is methane - CH4. It burns to produce water vapour and carbon dioxide. The water stays as vapour until the flue gas is cooled below the dew point of the flue gas. A MILLION miles from what you have stated.
The very definition of dew point is the temperature at which saturation is achieved when moist air (or any gas) is cooled.
Assuming the flue gas is cooled to 55C, it will have a dew point of 55C, i.e. an RH of 100%.
Somewhere along the lines, it has been decided that condensing boilers should be designed, optimised and quoted for efficiency at 55C return/condenser/heat-exchanger temperature - a totally arbitrary figure.
 
I had a wireless one installed in January, can be taken anywhere in the house and works a treat. The previous owner had bridged the stat out because it was faulty and the TRVs just didn’t cut it, it was really difficult to achieve a stable temperature anywhere in the house. I actually leave it in its cradle in the living room but with the temperature set at 18.5c and the TRVs in other rooms set accordingly, it’s always a comfortable temperature.
 
Thats exactly how to do it, have one accurate room stat in a good stable place ie not near windows or doors then play around with the TRVs till you get the best compromise. The Trvs should be on there side as upright the heat from the pipe work is rising through them and giving incorrect temps.
 
So Vinny, are you arguing in favour of high boiler return temps?

or are you just arguing?

For a condensing boiler, indeed for any boiler, I am not arguing about anything.
What I am CORRECTING, is the total nonsense about how condensing boilers work.

So far as condensing boiler are concerned, they are designed/spec'd to operate with a return of 55C. That said, a lower return could not help but increase efficiency, which twotone pointed-out, thereby illustrating the nonsense of his own statement about how they actually work.

Consider the claim - water vapour from burnt natural gas condenses at 55C. So, there is no water vapour below 55C?????? Or is that only the magic water from burning natural gas? If it is, when does it stop being magic and exist again as vapour below 55C?

Yes, indeed, SOME water will condense, because the dew point of the flue gas is above 55C. It also has precisely nothing whatsoever to do with what was burnt to generate the water vapour - it could be wood or oil (though not coal - that is essentially carbon, so burns almost water-free).
 
Thats exactly how to do it, have one accurate room stat in a good stable place ie not near windows or doors then play around with the TRVs till you get the best compromise. The Trvs should be on there side as upright the heat from the pipe work is rising through them and giving incorrect temps.

Nearly correct it's nothing to do with the heat from the pipe-work it's the heat from the rad but honestly it doesn't matter now because the valves are bi-directional so can be installed in any orientation, TRVs are not that important anyway they're only for comfort and add very little to the efficiency of the heating system, less than 5%.
 
The TVRs are there to measure the temp of the returning convected air stream that the radiator is causing ie the cooler air rolling along the floor.
 
Seems to me people are getting confused between control units, boiler thermostats, room thermostats, and radiator thermostats.

Maybe there's a primer online somewhere ?!
 
I'm feeling fortunate to have a basic system, boiler with two £3 Tesco time switches (one for each pump), TRVs in every room.

It works.
 
I had a wireless one installed in January, can be taken anywhere in the house and works a treat. The previous owner had bridged the stat out because it was faulty and the TRVs just didn’t cut it, it was really difficult to achieve a stable temperature anywhere in the house. I actually leave it in its cradle in the living room but with the temperature set at 18.5c and the TRVs in other rooms set accordingly, it’s always a comfortable temperature.


Are these reliable? I'm thinking of getting one but my experience with the reliability of new central heating stuff (timers, valves etc) has made me wary, though maybe I've been unlucky.
 
These are excellent, they're cut down versions of Honeywell CM927.

I've been installing both versions since about 2006 and have had maybe 5 fail out of well over 100.

I've one in my own house (mentioned in a previous post).

BTW, they're really only suitable for combi boilers however you can install them on traditional Y or S plan systems but it's a bit of a faff (you need to use relays) and probably pointless with those systems.
 


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