New wireless digi thermostat and TRVs- house not warming up

[croz]

Recently replaced 30 year old room thermostat with new digital model and moved it - on plumber's advice, from dining room to hallway (small 4 bed house). Wireless link to boiler (new condenser boiler installed separately with new pump 2 years ago - but room thermostat not replaced at that time). Also have just installed TRVs on all rads except 2 in hallway (at same time as installing new room stat).

Have had room stat set at 20 or 21 but struggling to get temperature above 17-19 at the moment with stat set to 22 - (Alpha) boiler stat set at between 6 and 7. Grundfoss pump set at speed 2. Would increasing to speed 3 be of any use ....or should I just wear more warm clothes ....?
Is my system likely to be out of balance ? (No - I don't have it on all day ... normaly on between 6AM and 11AM and then from 4PM to 11PM ...roughly)

 

[gigz]

Not familiar with this boiler but i would have thought boiler stat needs turning up to max to give room stat full control (boiler stat might be turning off first) What room are you taking temp reading from ?

 

[croz]

Taking temp from the digi stat in the hall (it shows actual temp and temp set). Boiler is Alpha CD18R - hall temp right now (10PM) is 18 - with stat set at 22 - and heat has been on since 4PM. Both hall radiators are hot - no air or anything obvious. Boiler manual suggests normal setting for boiler stat is 5 or 6 (max is 9). House was never roaring hot with the old room stat but is definitely not warm today

EDIT - is it safe to run bolier with stat set to max at all times ??

 

[gigz]

Your boiler will only be on max if you turn the room stat up to max as well, the boiler stat could be over-riding the room stat

 

[croz]

OK thanks will give it a go ..leave the pump alone though ..right ?

 

[croz]

Didn't seem to make any difference - stat showing 17.5 this morning at 8AM after 2 hours heat. Maybe I should move it to a different part of the hallway - although not a big space. What bugs me is that if the temp never gets to the set value - the stat will be calling for heat constantly - the boiler will be running constantly and the gas bill will be through the roof. Net - money spent on new stat wasted ?

 

[D_Hailsham]

Recently replaced 30 year old room thermostat with new digital model and moved it - on plumber's advice, from dining room to hallway (small 4 bed house). Also have just installed TRVs on all rads except 2 in hallway (at same time as installing new room stat).

Was it getting hot OK before you installed the wireless stat and the TRVs?

(Alpha) boiler stat set at between 6 and 7.

Was it at this setting with the old stat?

Grundfos pump set at speed 2.

Was it at this speed with the old stat

Is my system likely to be out of balance?

Probably. Did the installer rebalance the system after the TRVs were installed?
If so, how did he do it?

... boiler stat needs turning up to max to give room stat full control (boiler stat might be turning off first)

I agree

 

[croz]

Answers in order ...

Yes - but of course with the non-digi old stat we coudn't see what the actual temperature was !

Yes.

Yes.

Not as far as I know.

Right now (8PM) it's up to 21 and nice and warm ...but seems Mrs Croz has had the heat on most of the day ......so maybe it was just a question of getting the house properly warmed up. I have turned the boiler stat to about 7.5 now and I'm just opening all the TRVs to max 5 with all doors open to see if we can get the whole house nice and toasty. Any advice on how to balance would be great (I can call the man tomorrow - he's done a couple of jobs for us so won't have a problem with that .....but if I don't need to - and I should find something else to worry about ....would be good !)

 

[D_Hailsham]

Right now (8PM) it's up to 21 and nice and warm ...but seems Mrs Croz has had the heat on most of the day ......so maybe it was just a question of getting the house properly warmed up. I have turned the boiler stat to about 7.5 now and I'm just opening all the TRVs to max 5 with all doors open to see if we can get the whole house nice and toasty.

If it is taking all day to get the house up to temperature, then either the radiators are not large enough or the boiler is not giving enough heat.
Turning a TRV to a higher number does not make the room heat up any quicker. It just means that the room will reach a higher temperature before the TRV closes down.

Balancing procedure:

(I wouldn't show this to the engineer - he may take offence!!)

You will need either two clip on pipe thermometers (£12 each) or an infrared thermometer (about £25 from Maplin). I have used both and prefer the infrared as it has a faster response, is more accurate and can be used for other things, e.g checking the temperature distribution over the surface of a rad.

1. Turn boiler off and allow to cool
2. Make sure HW is turned off
3. Open all LS valves fully; remove all TRV heads and open all manual rad valves fully.
4. Turn the boiler temp to 75°C and bring system up to temperature.
5. Check, by feel, the order in which the rads warm up and make a list.
6. Adjust the bypass (if fitted) as per mfr instructions
7. Measure the temperature differences between the flow and return pipes at the boiler. What it should be will depend on the boiler -refer to the installation manual. If the temperature is not right, you need to adjust you pump speed (higher speed gives smaller difference and vice versa). Set the speed to give a difference as close to the mfrs recommendation as possible.
8. Turn the boiler off.
9. Close all lockshield valves. Leave TRV heads off.
10. Restart boiler
11. Go to first rad in list made in step 5
12. Attach the pipe thermometers (if used) to the rad and open the LS valve a quarter turn.
13. Wait until temperature has stabilised on the two thermometers (or use the IR thermometer to measure flow and return temp in the pipes adjacent to the valves). If the difference is smaller than that at the boiler, close the LS valve a fraction, or vice versa. Wait until the temp has stabilised and check again.
14. When you are happy with the first rad, move on to the next on the list.
15. Repeat steps 12, 13 and 14 for each rad on the list.
16. When you have reached the last rad, check the boiler temp difference and adjust pump speed if necessary.
17. Go back to the first rad and test it is still giving the correct difference
18. And so on, going round and checking the temperature difference until they are all as near the required drop as you can make them. Don't expect perfection
19. Replace TRV heads and set to required temperature

A very small change in the amount a LS valve is open can have a considerable effect on the temperature difference. Because of the way LS valve are constructed, it is virtually fully open when it is one and a half turns open. So most adjustment will be within one turn from closed.

If you find that the wall thermostat is turning the boiler off before the TRVs in the other rooms work, you should close the wheel valve slightly, so the rad gives out less heat and the room/hall warms up slower. It's a matter of trial and error.

 

[croz]

Well - I did ask !
Thanks for that ...although I don't think it's something I want to attempt - so we'll see how it goes when I am at home all day tomorrow ...and it might be a call to the friendly plumber !