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Dave876
Not sure how long this has been happening but some symptoms have been there a while - only noticed now as the house is cold in this weather plus I had a stuck TRV.
House was extended - new radiator on the longest run has never gotten properly hot - it's usually cold. 11 rads total, worcester bosch greenstar CDi30 boiler, grundfos alpha 1 pump.
Everything is running but none of the rads get particularly hot as the boiler is short cycling. Tried balancing the rads but even with all trvs and lockshields open still short cycling. pump is running full speed. All rads do get hot at least depending on what's open or closed. If I shut all other rads down then the last radiator does get hot but limited heat due to short cycling boiler.
No matter what's happening - feed from the boiler gets hot as expected (and the boiler goes up to expected temp) but the return is never hot enough to be even close to the same temperature.
Boiler was serviced 2 years ago, system drained, flushed and refilled, bypass valve replaced. System is s-plan (not zoned) and both valves work fine (one replaced not so long ago). Magnaclean was checked a 2 months ago.
I don't think that the pump is up to the job hence can't push the water round fast enough for the boiler. Or have I missed something?
I think (from an online chat with Grundfos a while ago!) the next one up is UPS2 25-80?
Any help or advice appreciated!
House was extended - new radiator on the longest run has never gotten properly hot - it's usually cold. 11 rads total, worcester bosch greenstar CDi30 boiler, grundfos alpha 1 pump.
Everything is running but none of the rads get particularly hot as the boiler is short cycling. Tried balancing the rads but even with all trvs and lockshields open still short cycling. pump is running full speed. All rads do get hot at least depending on what's open or closed. If I shut all other rads down then the last radiator does get hot but limited heat due to short cycling boiler.
No matter what's happening - feed from the boiler gets hot as expected (and the boiler goes up to expected temp) but the return is never hot enough to be even close to the same temperature.
Boiler was serviced 2 years ago, system drained, flushed and refilled, bypass valve replaced. System is s-plan (not zoned) and both valves work fine (one replaced not so long ago). Magnaclean was checked a 2 months ago.
I don't think that the pump is up to the job hence can't push the water round fast enough for the boiler. Or have I missed something?
I think (from an online chat with Grundfos a while ago!) the next one up is UPS2 25-80?
Any help or advice appreciated!