Central heating and TRVs

nat_scott22

Hi, I have a really old Worcester combi boiler in my rented house. There is no central thermostat in the house, but each radiator is fitted with a TRV. I am wanting to know how best to set the boiler and TRVs to be most economical but that so I am warm (it's an old house!) At present, the boiler is set at 3 (goes from 1-5) and the TRVs are set at 3, and I turn the heating on/off as I require it, currently on for about 3 hours per night (gas central heating). If anyone knows the most economical way of having my heating set please let me know! Thanks, Natalie

CashStrapped

Hello..

First check out this thread, and specifically my second post wish describes how all the parts of a central heating system work.

https://forums.moneysavingexpert.com/discussion/5536892

In your specific case, it is a bit of trial and error.

You want to turn the boiler dial (to change the water temp in the radiators) to a setting that is high enough to actually heat the rooms.

I prefer the minimum heat setting possible to get the room warm and maintain that warmth. Otherwise you get burning hot radiators for short periods, until the TRV's cut them off. This can lead to short but quick temperature changes.

Then (with the TRV's on 3) see how warm a room gets...

The only thing a thermostat does is turn the boiler off when it is not needed or when room is at the set temp [on the thermostat].

Without one, you just have to do these two things manually. Or use the timer.

If you get those three things balanced then it should work pretty efficiently.

Cardew

As said above, for every property it is a case of 'trial and error' - there is no 'one size fits all' solution.

Norman_Castle

Not aimed at the OP. Quite a few people I know have their TRVs set at maximum making them pointless. When they are set at 3 or III this is normally 70 degrees. The III setting should be the starting point. Once the heating has been on for an hour adjust them by small amounts if necessary. Once set they rarely need adjusting.

TRVs are an off switch which switch that radiator off when the room is at the set temperature. The room will warm up as quickly regardless of the setting. They save money by preventing rooms being overheated.

matelodave

It's a common misconception that turning the TRV's or room stat if you've got one up will warm the room quicker - it won't, it will just get hotter eventually.

Ideally set them to about 2-3 (or 68-70F or 18-19C)to see if the room gets warm enough, if not increase it a little bit until it does. If the room won't get up to temperature with the TRV's full on then the boiler temperature isn't high enough.

Its the boiler temperature that controls how fast the room heats up, so setting it to around 3-4 should be about right. If the rooms take ages to warm up or dont get hot enough with the TRVs wide open then increase it until it does. As said it's a bit of trial and error. You might need the boiler a bit hotter in the depths of winter and turn it down a bit in the spring and autumn.

Ideally the rads should get quite hot when the heating starts up and then when the room is warm enough they should be about lukewarm.

Set your time clock to turn the heating on about half an hour before you want the room warm and off again about an hour to half an hour before you go out or go to bed to optimise your heating periods.

Once you've seen how it all works and how comfy you are then little tweaks of the timers and temperatures should make it nice and comfy without wasting heat when you aren't there (or tucked up in bed)

weddingringman

Is it therefore true that by having the TRVs set to max, the boiler is running for a larger total duration while the heating is switched 'on'. So if I set many of the TRVs to 3, for the 2 or 3 hours the heating is scheduled to come on, it will shut down periodically during this time as the temperature Ive set my boiler to is achieved.

(I dont have a thermostat and I am concerned my boiler is running flat out for the entirety it is switched 'on'.)

CashStrapped

No, not exactly.

The trv's do not turn off the boiler, they turn off the radiator only and leave the boiler running. Although they may allow a boiler to maintain the set water temperature more easily, therefore using less energy.

How hard the boiler is working is determined (mainly) by the setting on the boiler (i.e how hot you want the water in the radiators to be).

The ideal method is to have the setting on the boiler and the lowest setting that creates a consistent comfortable temperature.

You then have to make use of the timer and/or manually turn on/off the boiler if you do not have a thermostat.

The TRV's just control the individual room temperature. So if one room heats up and says warm much quicker and longer than others, the TRV turns that radiator off. This means the boiler has to work less hard as it is heating one less room for a while.

If that room cools down too much the TRV reactivated the radiator.


If you read my second post in the other thread (linked in post two above) I go through each control systematically. It is a bit clearer.

weddingringman

My household heating schedule has historically been ruthless! With the heating only coming on for, say, an hour in the morning, an hour at 4pm and an hour at 6pm!

A new addition to our family has caused a bit of a meltdown however... with the poor boiler running day and night! So need to get something more sensible programmed in!

weddingringman

We only averaged £60 per month on gas and electricty last year.

Cardew

weddingringman wrote: »

Is it therefore true that by having the TRVs set to max, the boiler is running for a larger total duration while the heating is switched 'on'.
(I dont have a thermostat and I am concerned my boiler is running flat out for the entirety it is switched 'on'.)

You state in the opening post you have a really old boiler, and no room thermostat.

Most boilers now can 'modulate' their output i.e. turn down output. However some older boilers haven't that facility and run 'flat out'(as you put it).

However with either type of boiler they won't run flat out all the time the boiler is switched on by the timer.

When the room is up to the temperature set on the TRV the radiator is turned off. Thus the water in the pipes will reach the temperature set on the boiler(setting 3 of 5 in your opening post) and the boiler will shut down.

Putting the TRVs to maximum will simply raise the room temperature and the point at which the TRV closes.

matelodave

Ideally you need a room stat that turns the boiler and pump off when the reference room is up to temperature, otherwise the boiler and pump will just run to maintain the boiler temperature. keeping the boiler and pipework hot all the time just wastes energy.

Even old fashioned systems had the pump controlled by a room stat although the boiler cooked away continuously under the control of it's own stat.

I'd be inclined to investigate the installation of a wireless programmable room stat to turn the boiler and pump on and off when required

A Salus one like this https://www.mrcentralheating.co.uk/salus-wireless-programmable-room-thermostat-rt500rf-pack?utm_source=google_shopping&gclid=CKeB6ImV088CFRITGwodxJgNOA#.V_0SbuArLIW is easy to install.

The receiver unit goes next to the boiler and you can move the thermostat around to find the best place. It's programmable so you can set up different temperatures at different times of the day and even on different days of the week.

It would probably save you quite a lot of money in the long run