New heat exchanger left me with no hot water
- Thread starter Howard123
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Look at the flow switch spindle
Fact that it is pushing out for central heating ( due to higher differential across flow and return), it is indicative the flow manifold is fine
During hot water demand, flow/ return differential is just sufficient to eject the spindle to activate the switch. Look at the spindle while some one else runs the hot tap. If my diagnoses is correct, you will find spindle comes out a little but not enough to operate the switch ( which leads to fan running etc)
Run heating, no hot tap run, you should see the spindle pushes out solidly
Now hot water demand- spindle may ease back to release the switch or continue to hold to give you hot water ( the spindle push requires more energy but can be held in place with reduced energy)
My though is air in the system which is being compressed to detriment of solid push of the flow spindle during hot water demand. Air ingresses obviously when you replaced the heat exchanger. Check the cap on the air vent that is located on the pump- it should be loose to allow air to escape
Huge thanks to @ianmcd - you are a real star and I cannot thank you enough for all your help and time with this. I tested the diverter valve and it appears to be working. I also tested the flow switch sensor with a magnetic screwdriver and that also seems fine. Sadly still no HW on demand.
@DP thank you for your suggestions - I did as you suggested and although I had to turn the HW on and off several times to be sure, the spindle does indeed come out very, very slightly (but obviously not sufficiently). The air vent is an auto air vent but there is indeed a cap on the top which I have loosened a little. What would you suggest I do to get the air out?
@DP thank you for your suggestions - I did as you suggested and although I had to turn the HW on and off several times to be sure, the spindle does indeed come out very, very slightly (but obviously not sufficiently). The air vent is an auto air vent but there is indeed a cap on the top which I have loosened a little. What would you suggest I do to get the air out?
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I have tagged @shambolic for you, he works for ideal, he may have some insight in to a common problem with your boiler, I doubt very much if it is air or the CH wouldnt work
As already said there is a restriction somewhere
no there is a diagphragm, that pushes the spindle, there is no problem in the housing as it comes out fully for CH it is the sensing pipes when HW is demanded that is causing the problem
Run the boiler in hot water mode couple of times, ensure system Pressure is about 1/1.25 bar. Make sure cap is loose to allow air to self purge when pump runs
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Are there sensing pipes on this boiler?
OP, are you sure that you have properly bled the pump of air?
This model is very sensitive to air in the pump.
You need to just loosen the large silver colour screw in the middle of the pump with the hot water demand selected so that the pump is running. A little water will come out which can be absorbed in a small old towel.
This model was built by Biasi and is virtually the same as the Biasi M90 !
This model is very sensitive to air in the pump.
You need to just loosen the large silver colour screw in the middle of the pump with the hot water demand selected so that the pump is running. A little water will come out which can be absorbed in a small old towel.
This model was built by Biasi and is virtually the same as the Biasi M90 !
But did you do it with the pump running?
I must say I have repaired a lot of that model as I used to do some warranty repairs for Biasi. And Biasi boilers were very popular with landlords as they were very competitively priced.
But apart from bleeding the pump I cannot think of any reason for the poor flow switch activation. That assumes the diverter valve is working properly.
I must say I have repaired a lot of that model as I used to do some warranty repairs for Biasi. And Biasi boilers were very popular with landlords as they were very competitively priced.
But apart from bleeding the pump I cannot think of any reason for the poor flow switch activation. That assumes the diverter valve is working properly.
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