TRV's

[Confused and broke]

Please help!!

We have recently moved into a new house (to us) and are completely baffled by the central heating system. It is run off LPG to a boiler that seems to have a thermostat in the form of an 'output temperature' control on it. We have no thermostat in the house but have these TRV's (Drayton and Honeywell) on all the radiators (except in bathrooms(2)))
The problem is that we seem to be using a tanks worth of gas (£400) each month, and that's just with the heating on for a few (2-3) hours in the morning and evening, and the house is still freezing (3bed detached, not that big!!). What I want to know is do I maximise heat output by turning all the TRV's to max or will this cost me more and should I instead have them all turned down low and on constantly?
In summary - I guess my question is - does the setting of the TRV's affect the gas consumption? and how can I reduce my bill (without double glazing etc which will all be done, just not immediately!)

Thank you for any help/advice
(15yr old boiler has been serviced, but is old and inefficient and will be replaced during building work this summer!)

 

[MANDATE]

Firstly you should realize on the other side of the radiator is a lockshield valve. So it depends if these have been left fully open and all control coming from TRVs.
If lockshields are fully open and the TRVs are fully open, thats everything on max for every room, unless you up the boiler stat
The TRVs can only reduce the flow through a radiator which reduces the temperture. With reduced tempertures gas useage must be less.
Regarding the bathroom radiators, I believe they or at least one of them acts as a by pass and that is why it don't have a TRV.
Also not all bathroom radiators are on the heating side, mine is on the hot water side so with heating off bathroom is still warm.
I suppose insulation is the key, Losing heat at a quicker rate than it can be supplied has to be costly.
Not sure if this helps or am I stating what you already know.

At £400 per month I'd be concerned. I buy oil twice a year (1000 litres)
One delivery Dec to March and then Mar to Dec approx. Prices keeps rising. Last delivery £450.

 

[D_Hailsham]

I know it's too late now, but:

1. Did you ask your surveyor to arrange for a report on the central heating system?
2. Did you ask the vendors for copies of their utility bills?

a boiler that seems to have a thermostat in the form of an 'output temperature' control on it. We have no thermostat in the house but have these TRV's (Drayton and Honeywell) on all the radiators (except in bathrooms(2))

The basic problem is that the boiler does not know when to turn off
The thermostat on the boiler is there only to control the temperature of the water leaving the boiler. The colder the water returning to the boiler, the more fuel will be used heating it up. Even when all TRVs have closed down there will always be some heat loss from the two bathroom rads, so the return water will always be lower than the flow and the boiler will continue running.

Get a room thermostat fitted, e.g. Honeywell CM900 range. It won't be a waste of money as you will be able to keep it when you replace the boiler.

The problem is that we seem to be using a tanks worth of gas (£400) each month, and that's just with the heating on for a few (2-3) hours in the morning and evening, and the house is still freezing (3bed detached, not that big!!).

You are not running the CH very efficiently You warm the house up in the morning, so you can get out of bed without shivering, then you turn everything off when you go to work and the house cools right down again until it comes on ready for you to return in the evening. It would be better to maintain the house at a steady temperature all day. The CM900 would allow you to do this. It calculates when to light the boiler so you get up warm; on very cold days it will light anything up to two hours earlier, on warmer days it may light only 15 minutes early. You tell it the time you want the house to be warm by and what temp and it does the rest!

It also allows you to set up to six time/temperature combinations. So you could set it to be 21C for 0700hrs; 18C at 0900hrs ; 21C at 1800hrs and 10C at 2300hrs.

do I maximise heat output by turning all the TRV's to max or will this cost me more and should I instead have them all turned down low and on constantly?

Of course if the rads and boiler are not big enough the rooms will never get up to temperature and the TRVs will never shut

(15yr old boiler has been serviced, but is old and inefficient and will be replaced during building work this summer!)

There is a useful Recommended Boiler Size calculator at the Sedbuk website. Its no substitute for a properly worked quotation with heat loss calculations etc., but it is a good guide as to the size required.

 

[Confused and broke]

thank you very much for your help!

the tank was full when we moved in (aug ) and this seemed to last us til november - it's been filled 3 times since then and we've had the heating off since new year (v.v.cold!!). Looking at previous statements we seem to be running more gas, but not hugely so. But then there are two of us and they were a family of 6!

We had the boiler serviced and assume we would smell any leaks. I spoke to a woman at calor who tried to convince me that although the usual rate of gas consumption for our boiler was about 15l per day (Gods knows what she based this one - she said something about using the cooker for an hour a day - which we don't!!), it was fine that we are using about 22 ( i think these were the figures).

I guess maybe a room stat might help, But the heating never seems to get the rooms warm anyway - and definatly not at justified cost.

Maybe i''ll try out local calor man again and get him to have another look.

Thanks for you help though - really appreciated!

 

[easyflow]

Did no one tell you running a boiler on LPG is much more expensive than piped gas.