Wireless thermostat question

[spoony77]

Hi people
We have a wireless thermostat in our living room and it has always kept the temperature nice and stable.
However we now have built a rear house extension that will be used as a play room and dining area, even though we put a big radiator in there it never gets warm as i presume the thermostat cuts out because the small living room is at temperature.
So what are my options to get this room warm can i just move the wireless stat to the new back room or will it mess with the rads own trv valve?
Will i need to then find a trv head for the living room radiator which has been removed?
Any advice appreciated.

 

[D_Hailsham]

Was the system rebalanced after the extension's rad was installed?

 

[spoony77]

Hi there, no balancing was done as far as im aware.
Is this a big job?
How much would a plumber charge me?

 

[D_Hailsham]

It's not a big job, but it can be time consuming if done properly. The chances are you will get better results if you do it yourself!

I can give you instructions, but it would help if I knew a bit more about your system.

Which boiler do you have (make and exact model)?
Do you have a hot water cylinder?
How many motorized valves (only of you have a HW cylinder)?

Do you know where the new rad was connected to the original circuit?, i.e was it connected to another rad or was it connected to the main pipe?

 

[spoony77]

Hi there
It's a vokera compact he combi boiler.
The new rad was just piped over from an existing rad.
Regards

 

[vulcancontinental]

Some Compact HE's had 5m head pumps fitted and some 6m, depends on boiler output. A balance will probably do it. Those rads closest to the boiler turn off on the lockshield then open it up a quarter of a turn. The further you go open up more to about to one turn maybe a turn and a half.

Probably throttling down the lounge rad will do most of the job.

 

[D_Hailsham]

OK, here's the quick method of balancing the system.

1. Remove all TRV heads and set rad wheel valves to max open (anticlockwise)

2. Close lockshield (LS) valves (clockwise) then open by one-third (1/3) of a turn.

3.Turn on boiler and set the heating temperature so it is above the Auto (SARA) sector. This ensures a constant water temperature.

4. Set the room thermostat to a high temperature so the heating doesn't keep going on and off.

5. Let everything heat up.

6. Check, by touch or with a thermometer, the temperature of the return pipe to the boiler. (That's the cooler pipe.)

The aim of balancing is to have the return temps for each rad the same. This is done by adjusting the LS valves. Open the LS to raise return; close LS to lower return. Adjustment should be made in very small steps, 1/10th of a turn or less.

7. Check the return pipe temperature of the all radiators.

8. Close very slightly the LS valve on the rad with highest return temp.

9.Wait 5 minutes.

This will affect the other rads, so you have to repeat 7 and 8 until all return pipes seem to be the same temperature. You also need to compare them to the return pipe at the boiler.

Do not expect perfection, even if you are using a thermometer.

When all rads have been balanced, replace the TRV heads, set the boiler stat and room stat to the usual settings.

If you find that the room stat turns the boiler off before the extension reaches temperature, slightly close the LS valve on the living room rad. This will reduce the rad output so it will take longer for the living room to reach temperature.

 

[vulcancontinental]

D_Hailsham's a bit more careful about it than I would be because it's only a domestic system but good point about the SARA function which I forgot and I work for Vokera.

Anyway you get the idea and try to use the SARA function all the time if you can, the boiler is more efficient; it's the section of the heating temperature selector on the boiler marker auto.

 

[spoony77]

That's a very informative and helpful answer thank you .
Can I just ask when you say turn the lockshield valve a quarter of a turn do you mean like from 12 o clock to 4 o clock on a clockface? When I practiced on one rad this small turn from closed didn't seem to even open the valve enough to let water through?
Also will this balancing be doable to an acceptable standard withought a thermometer of any type?
Thanks again.

 

[gas112]

by never gets warm do you mean the rad or the room ?

 

[spoony77]

by never gets warm do you mean the rad or the room ?

Both!

I assumed the Sara function of the boiler was totally negated by me using a room stat? If that's not the case I will make sure I dial it back into this section if it helps with efficiency?

 

[D_Hailsham]

Can I just ask when you say turn the lockshield valve a quarter of a turn do you mean like from 12 o'clock to 4 o'clock on a clockface?

Yes; however 12 to 4 is one third of a turn (120°), 12 to 3 is a quarter turn (90°).

When I practised on one rad this small turn from closed didn't seem to even open the valve enough to let water through?

That's probably because all the other LS valves are so far open that they are pinching all the water. Remember the water will take the path of least resistance. Setting all LS valve to 1/3 turn open means that the resistance through each will be approximately the same.

How far the LS valve needs to be open will depend partly on the size of the rad. As a general rule, the larger the rad, the more it needs to be open.

This may seem small, but the typical LS valve is fully open at about 1½ turns. Now a 15mm pipe can carry about 12kW at 20C differential, so a valve 1/3 open will allow about 2.5kW to pass.

Also will this balancing be do-able to an acceptable standard without a thermometer of any type?

It will be OK, provided the return pipes at all rads feel approximately the same temperature and there is a noticeable difference between flow and return.

 

[vulcancontinental]

Very few rad valves are proportional, only the more expensive. The knob may rotate 6 complete turns but most are useful for balancing up to around a turn and a half.

Those closest to the boiler on the same storey open a quarter turn or until the hissing noise disappears. Gradually open those further away to around a turn-ish.

The one you have to pay attention to is the one before the new rad, turn that down and the new rad to max.

SARA works fine with a room stat. Condensing boilers are more efficient the cooler they run. Most people set the heating selector to maximum, a flow of around 75 to 80 degrees which means the boiler will never condense though it would still be more efficient than a no-condensing boiler. You only need maximum heating flow temp when it's coldest which is not most of the year.

SARA runs the boiler between 55-65 degrees which is fine for most of the year chilly weather but not freezing weather.

When the boiler is set in SARA if your system controls are calling for heat to the radiators it initially operates the boiler at the low temperature.

Should the call for heat remain for over 20 minutes the boiler thinks to itself the heat loss is greater than normal (colder weather) and without any input from the user adds 5 degrees to the heating flow to put a little more heat into the house.

It does this for another 20 minutes and should the room thermostat still be calling for heat without interruption would then add another 5 degrees and so on until the room thermostat says satisfied or the boiler hits maximum temperature.

It isn't as good as weather compensation or modulating thermostats that adjust the boiler flow but it's free and on you boiler and improves efficiency a little. It's just 20 minutes late in reacting whereas more sophisticated controls are predictive.

 

[spoony77]

Just a quick update to say that rebalancing the system worked a treat!
It appears all my lockshield valves were fully open on all my rads and when I closed the upstairs ones to 1/4 turn open only, suddenly my new rad started finally getting some heat - in fact it got so hot I might need to use the TRV and dial it down a little!!
Thanks again to all that helped it is very much appreciated.

 

[D_Hailsham]

it got so hot I might need to use the TRV and dial it down a little!!

Each number on a TRV represents a room temperature. It varies from brand to brand,but 3 to 4 is normally 20 to 21C. You set it to the temperature you want in the room and the TRV does the rest. A bit like a cruise control on a car.