Having problems balancing rads, worcester 28cdi combi, 8 rads in old part of house without trv's and a new ground floor extension with another 8 rads all with trv's (for b/regs) the furthest rad from the boiler in the extension is approximately 26 metres from the boiler. I can get all the rads hot in the extension by turning off those in the house, so i know the system is working, does it just require more balancing, or could the fact that half of the rads haven't got trv's be causing any problems (wondered if the valves create more resistance) any advice appreciated thanks
TRV's or not
- Thread starter andyandy2
- Start date
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Sounds more like a pipe sizing problem to me, or the pump isn't powerful enough to cope, or both.
Don't know about WB but some combis have a setting for adding an extra external pump to cope with large systems.
Don't know about WB but some combis have a setting for adding an extra external pump to cope with large systems.
Thanks gas4you, Pipework is 22mm as far as possible with shortish runs of 15mm to rads. The original system was put in about 9 years ago, boiler was supposed to be adequate for the proposed extension (i think the rads in the extension add up to about 1/3 of the boiler capacity) I remember reading somewhere on here that boilers are factory set at about 50% of there capacity, is this a possibility
Combis are not factory set as they are modulating, i.e. will run at full power when heating first comes on then the flame reduces as water is heated.
I doubt whether it is the boiler too small. It's a circulation problem or restriction.
22mm should carry up to 60,000 btu's (18Kw approx) any more would need 28mm.
Check whether ball-o-fix type isolaters have been used to attach the new extension. If so these cause a great restriction in flow as they are only about 6mm internal diameter.
I doubt whether it is the boiler too small. It's a circulation problem or restriction.
22mm should carry up to 60,000 btu's (18Kw approx) any more would need 28mm.
Check whether ball-o-fix type isolaters have been used to attach the new extension. If so these cause a great restriction in flow as they are only about 6mm internal diameter.
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I put in all the pipework and rads for the extension, and purposely made sure there are no isolating valves for that reason, thanks for your help anyway, think i will try balancing again before i go any further, would the original rads benefit from trv's ?
Today's regs state that all rads except the one in the room where the room stat is must have trv's.
These would not cure the latent fault, but 'help' in that when they shut off the water will get pushed to the others.
These would not cure the latent fault, but 'help' in that when they shut off the water will get pushed to the others.
Start off with balancing the radiators, this is the most likely cause. Depending on how clean the system is, it could well mean that the pump is due for replacement. Most worcesters can be range rated, calculate the output of the rads together and check how much gas the boiler uses when on heating.
There are instructions on balancing systems with TRVs at:
http://www.invensyscontrolseurope.c...F-5323-48E3-BD8B-B33ADB04A2E5/7139/D348v2.pdf
Although it is for Drayton TRV's the advice is useful as it shows that you have to set the TRV to a specific amount open using the decorators cap otherwise the system will never balance properly!
http://www.invensyscontrolseurope.c...F-5323-48E3-BD8B-B33ADB04A2E5/7139/D348v2.pdf
Although it is for Drayton TRV's the advice is useful as it shows that you have to set the TRV to a specific amount open using the decorators cap otherwise the system will never balance properly!
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