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One for the heating/boiler engineers out there.
sdh2903 - 11/12/14 at 04:45 PM

Hi all.

We recently had a new Alpha condensing combi boiler fitted and so up to now has been great and very efficient. However now the heatings on more we've noticed an issue with the hot water.

When the heating is on and you turn a hot tap on we get a surge of very very hot water then it settles down to its set temp after its been running for a while. Looking at the readouts on the boiler it can be as high as 70-80 degrees before it settles down to 40 odd degrees. We have it set quite low due to our 3 year old washing her hands.

This is definitely more noticeable at the taps closest the boiler but can be felt all round the house.

We've had alpha out to it and they replaced the diverter valve and the engineer said it was sorted however I didn't notice til afterwards that the crafty bugger had turned the radiator output right down.

Is this a normal phenomenon with a modern combi? Or should I be getting them back out? We had a worcester bosch at the old house and we never had this issue.

Cheers
Steve

rotax78 - 11/12/14 at 04:59 PM

Have they changed the diverter valve or just the actuator? could be crap stuck in the diverter valve (seen this lots) which allows primary water to trickle through the plate to plate heat exchanger, heating the static domestic hot water on the other side of the plate to plate as it does so. Or Could it be you have it set to hot water pre-heat? this basically keeps the plate to plate heat exchanger at a high temp, so that when you open the hot tap you have no "dead leg" of cold water within the boiler.

[Edited on 11/12/14 by rotax78]

adam1985 - 11/12/14 at 06:36 PM

What have they turned the output down to? How many radiators do you have

sdh2903 - 11/12/14 at 08:56 PM

quote:
Originally posted by rotax78
Have they changed the diverter valve or just the actuator? could be crap stuck in the diverter valve (seen this lots) which allows primary water to trickle through the plate to plate heat exchanger, heating the static domestic hot water on the other side of the plate to plate as it does so. Or Could it be you have it set to hot water pre-heat? this basically keeps the plate to plate heat exchanger at a high temp, so that when you open the hot tap you have no "dead leg" of cold water within the boiler.

[Edited on 11/12/14 by rotax78]


He told me he'd changed the valve. The item I saw was only 3-4 inches in length and 1 inch diameter ish. I would need to read the destructions to see about the pre heat we certainly haven't switched it on. I would certainly prefer the dead leg of cold rather than the little un getting scalded.

The radiator output was down below half. Only noticed this week when it went cold and the house seemed to struggle to get up to temp. We have a total of 11 radiators.