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- 6 Dec 2004
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Hello, we've been in this old house for a year now. The pumped CH system supplies HW:
first to upstairs rads + HW cylinder, then I suspect (in this order), to downstairs via a ground floor through passage rad, then to 3 rads in an ground floor only extension bldg, then (I suspect) all the way back to the boiler via two ground floor living room rads, and a halway rad.
When the temperature is not too cold, the last three rads heat up fine, but tonight at around +5 outside, they are stone cold. This often happens, and sometimes not just to those three rads - others on the ground floor sometimes do just not seem to come on or are barely warm. The duff rads show no signs of heat when the CH activates or afterwards. Yet on other, milder nights this year they have been piping.
The upstairs rads are always piping hot, so we had Myson 17 TRVs fitted to all rads in the house last year (to try and regulate heat to boost the downstairs ones - I'm waiting for someone to say that was a wrong move). I can't say if this rad problem was occuring before we had them fitted.
Other stuff: Tonight I turned the upstairs TRVs fully open, in case this would help things. The rad heat increased upstairs, but there was no change downstairs. We have one new CH on/off room stat in the 'cold' living room which is yet to be calibrated but which is fully open and the power light is on ok. I have bled all radiators and there is water coming out of all of them.
I have read that (and I quote from the good old RD red book) 'when TRVs are fitted to all radiators in a system, a valved by-pass should be provided in the system to maintain a minimum water flow through the pump'. I don't know if the plumbers fitted one of these. The book also says, 'TRVs do not swith off motorised valves to prevent boiler short-cycling' (visions of a boiler atop a uni-cycle). Relevant? Irrelevant?
Any advice much appreciated, I appreciate that any replies may take a while
Rick
first to upstairs rads + HW cylinder, then I suspect (in this order), to downstairs via a ground floor through passage rad, then to 3 rads in an ground floor only extension bldg, then (I suspect) all the way back to the boiler via two ground floor living room rads, and a halway rad.
When the temperature is not too cold, the last three rads heat up fine, but tonight at around +5 outside, they are stone cold. This often happens, and sometimes not just to those three rads - others on the ground floor sometimes do just not seem to come on or are barely warm. The duff rads show no signs of heat when the CH activates or afterwards. Yet on other, milder nights this year they have been piping.
The upstairs rads are always piping hot, so we had Myson 17 TRVs fitted to all rads in the house last year (to try and regulate heat to boost the downstairs ones - I'm waiting for someone to say that was a wrong move). I can't say if this rad problem was occuring before we had them fitted.
Other stuff: Tonight I turned the upstairs TRVs fully open, in case this would help things. The rad heat increased upstairs, but there was no change downstairs. We have one new CH on/off room stat in the 'cold' living room which is yet to be calibrated but which is fully open and the power light is on ok. I have bled all radiators and there is water coming out of all of them.
I have read that (and I quote from the good old RD red book) 'when TRVs are fitted to all radiators in a system, a valved by-pass should be provided in the system to maintain a minimum water flow through the pump'. I don't know if the plumbers fitted one of these. The book also says, 'TRVs do not swith off motorised valves to prevent boiler short-cycling' (visions of a boiler atop a uni-cycle). Relevant? Irrelevant?
Any advice much appreciated, I appreciate that any replies may take a while
Rick
