TRV and Combi Boiler - Reduce Energy Costs and Settings

[christoperrobinspipe]

Evening all

Newbie question, so apologies if this has been posted elswehere. I'm attempting to make my rented flat more energy efficient and reduce costs throughout the winter months. The radiators are all fitted with TRV's (excluding the bathroom). There is a Vaillant combi boiler and no room termostat. We have single pane windows throughout so heat loss is a major problem. Landlord is a stingy so and so, therefore no option to install or change exisiting setup.

1) I struggle to understand how TRV's reduce energy costs/waste if you have no room thermostat to control the overall boiler sytem. I have my combi boiler set at 65 degrees. If the temperature of the specific room reaches a certain level and cuts off the water flow via the TRV, how does this reduce energy if your boiler is still constantly running to pump hot water to all of the other radiators?
2) I've adjusted the TRV's to applicable levels in various rooms (e.g. spare room is set @ 2, kitchen @ 3, main bedroom @ 4, hallway @ 3, living room is set @ 5 )
3) People keep recommending having our boiler set to switch the heating on at specific times via programmable timer , but again, I struggle to understand how this is more energy efficient? I agree if the room is warmer then the rads have to work less hard to reach a certain temperature, but without a thermostat sensing the desired temp in the room, the boiler will just keep pumping water out at 65 degrees round the home? The boiler just keeps on running regardless.

Can someone please dumb this down for me? Currently I just switch the boiler heating on/off when required, knowing full well the boiler wont shut down if the rooms get to the temperature we want.

Any help or advice would be greatly appreciated

 

[Scott_D]

You need a room thermostat
It will turn the boiler off when the house is up to temperature

 

[christoperrobinspipe]

You need a room thermostat
It will turn the boiler off when the house is up to temperature

So how are TRV's more energy efficient without a room thermostat?

 

[jtsplumbing]

Get your landlord to fit one tell him the cost of the gas bills is to high, or if your happy get one fitted your self, RF unit would be best saves running cables around the flat

 

[townfanjon]

Room stat. Room stat , Room stat

 

[ShaunCorbs]

Do you have a programer on / for the boiler ?

 

[christoperrobinspipe]

Do you have a programer on / for the boiler ?

Yes - I do.

 

[christoperrobinspipe]

Get your landlord to fit one tell him the cost of the gas bills is to high, or if your happy get one fitted your self, RF unit would be best saves running cables around the flat

Thanks for the advice, however, my landlord is reluctant to spend anything. So I would have to incur the cost. I know of many others who have TRV's fitted yet have no room thermostat. So question is how are TRV's energy efficient when operated exclusively i.e. without thermostat.

 

[christoperrobinspipe]

Just to add, I had a plumber round recently doing some work on the flat. He recommended setting timer so heating comes on at certain intervals throughout the day from October through to March. Claimed it would cut heating costs. Again, I find this hard to understand without a room thermostat installed? It's the same as me turning it on and off manually via the combi boiler itself, surely?

 

[ShaunCorbs]

Yes - I do.

Best to get a room stat installed even if you do it off your own back should pay for its self easily

 

[christoperrobinspipe]

Best to get a room stat installed even if you do it off your own back should pay for its self easily

I am in complete agreement with you. But how are TRV's more energy efficient without a room stat?

 

[christoperrobinspipe]

I discovered below quote via a site earlier.

"The main problem with the absence of a room thermostat, however, would be when all the TRVs were turning the radiators “off”, but the timer and the boiler thermostat tell the boiler that heat is still required. In which case the boiler will keep firing-up and shutting down, but not delivering any further heat to the radiator circuit. The system will just be burning gas, and sending waste heat up the flue."

I'm fully aware that room thermostats are the way to go, but no one seems to be able to explain to me what the point of a TRV is and how they are more energy efficient when operated without the former? TRV's can operate in isolation but how do they help reduce energy costs if the boiler is continually running at a pre set temperature?

 

[Sharp Point]

A trv is individually keeping a room at a comfort level, a room stat is monitoring an average temp of the core of the house.
If all trv’s Eventually close, the boiler will still cycle using the built in thermostat.

I’ve always wondered what’s the point of a room stat, whilst using trv’s. I don’t make the building regs though, it’s left to some over zealous individuals who have to justify their salary probably.

 

[christoperrobinspipe]

A trv is individually keeping a room at a comfort level, a room stat is monitoring an average temp of the core of the house.
If all trv’s Eventually close, the boiler will still cycle using the built in thermostat.

I've read somewhere that there's an internal thermostat within combi boilers, judging the temperature of the water returning back to the boiler after it's passed through all of the pipes/radiators. This then determines if the gas needs to keep pumping to heat the water to the required temperature. E.g. 65 degrees.

On this basis, if all of the TRV's close then the water running from boiler, through the system and eventually back will be quicker (as less pipes and rads to run through) so the temperature upon return will be higher, so boiler will stop constantly trying to heat the temperature up to 65 degrees.

I know I'm not using the correct terminology here but am trying to understand this without a science degree.

 

[christoperrobinspipe]

Get your landlord to fit one tell him the cost of the gas bills is to high, or if your happy get one fitted your self, RF unit would be best saves running cables around the flat

Is this genunely something I could easily do myself or do I need a pro in? Sorry but don't know what an RF unit is. Could you offer some more info or recommendations on wireless devices? The prices range dramatically.

 

[Scott_D]

They range from 50-200 plus fitting of around 60-100£
What's your budget?

Without one the boiler will cycle on and off constantly

 

[fixitflav]

I've read somewhere that there's an internal thermostat within combi boilers, judging the temperature of the water returning back to the boiler after it's passed through all of the pipes/radiators. This then determines if the gas needs to keep pumping to heat the water to the required temperature. E.g. 65 degrees.

On this basis, if all of the TRV's close then the water running from boiler, through the system and eventually back will be quicker (as less pipes and rads to run through) so the temperature upon return will be higher, so boiler will stop constantly trying to heat the temperature up to 65 degrees.

I know I'm not using the correct terminology here but am trying to understand this without a science degree.

That's broadly right, and you've answered your own question. You must have at least one rad without a TRV (ie your bathroom) or a bypass. The TRVs close down at set temperature so the only heat (and gas!) used is to maintain temperature. The boiler fires on/off on its control-stat, or modulates if it has that feature. Maybe the bathroom overheats a bit, which uses some gas, but not likely to be significant. A room-stat might help a bit, it would need to be in the bathroom or another room with the TRV wide open, though in that case, depending on the size of the rad relative to the room it might switch the boiler off when other rooms are below TRV setting. If it's a wireless stat need to check the boiler is compatible. I doubt whether all Vaillants are, probably depends on the age, perhaps somebody will confirm or otherwise.

 

[gpbeck]

Think of it this way.
When your heating first starts all radiators heat up and emit maybe 10kw of heat, which is met by your boiler burning 10kw of gas.
When your place is nearly warm maybe a couple of rads left working, your boiler burns 2kw of gas to meet this demand.
In both cases boiler sends water out at 65deg, but much less flow of it when the place is nearly warm.
Hope this helps.

 

[christoperrobinspipe]

Thanks all! I've decided against trying to fit one myself after watching a few YouTube vids. With all the wiring etc. I think a pro would be better choice. Lets see what the landlord says...

 

[fixitflav]

Thanks all! I've decided against trying to fit one myself after watching a few YouTube vids. With all the wiring etc. I think a pro would be better choice. Lets see what the landlord says...

Thinking about this a bit more- maybe the boiler doesn't need to be anything special. If the remote roomstat

 

[fixitflav]

Thinking about this a bit more- maybe the boiler doesn't need to be anything special. If the remote roomstat operates a relay at the other end, all that needs doing is to identify the wire that would have gone to a wired stat, cut it and insert the relay in the gap. If you study the Y-plan wiring diagram you should be able to find it, but if you're not confident, it's a sparky job. Obviously keep the landlord in the picture. You can take the kit with you when you leave, just replace the relay with a connector.
I looked on the web but all the stuff I found only mentioned the roomstat (transmitter) end, you might be able to find more.
I have a W-plan system, the pump, diverter valve and junction boxes (aka strip connectors!) with the HW cylinder in the airing cupboard, the boiler downstairs. Your layout might be different.