Baxi Combi 80e, Water only warm, not hot.

[Maurice Flynn]

Evening all
Recently moved house. New house has a Baxicombi 80e

I had a problem with the hot water, the flow rate through the shower wasn't sufficient to trigger the hot water microswitch, unless I ran the washbasin tap first.

Believed it to be the DHW Diaphragm, so replaced it. Genuine Baxi parts, not cheap internet alternatives (just not worth the bother and time to do it on the cheap).

At the same time, replaced a leaking auto-air vent on the pump body.

All seemed to go well, apart from now I don't get any hot water, only luke warm ~40 degrees on panel front.

This is the older Baxiboiler with a hydraulic 3-way valve, not a motorised valve, so thought that perhaps the Diaphragm on the Central Heating diverter was outof balance with thenew DHWDiaphragm, so have replaced the Central Heating Diverter Diaphragm also.

Unfortunately still no Hot water.

Nothing apparently wrong on the front panel, no flashings lights. The DHW & CH Pins activate the microswitches when expected, both for DHW demand, only ch for CH demand. CH Pins retract after about 25 seconds from demand stopping, DHW immediately.

I have added sludge remover, flushed the system, re-pressurised the system..

Short of replacing the whole Diverter valve, does anyone else have any suggestions / ideas as to what may be wrong ?

Many thanks for your replies.

Maurice

 

[Maurice Flynn]

An Update

I have now replaced the entire Hydraulic assembly. Removed the Plate Heat Exchanger, flushed it through, de-scaled.

Still no Hot water, just luke warm.

Central Heating in the House is working, but doesn't seem to get to temperature as quick as it used to, though I could be imagining things after spending several nights pulling my hair out over this Poxy boiler.

Any thoughts as to what may be wrong with it still ? My thoughts are leading towards the Gas modulator/Valve, cue the Gas safe engineer.
I would be inclined to cut my losses and replace the whole thing, but looking to extend the house next year, so will be getting a more appropriate boiler then, sited in a different location.

Regards

Maurice

 

[jackthom]

With central heating OFF and the boiler supplying DHW, does the C Heating flow pipe get hot?

 

[Maurice Flynn]

Many thanks for the Reply Jackthom.

The issue seemed to be related to the Gas valve, which I was not willing to mess with, so called in a Gas Safe Heating engineer.

He has diagnosed the issue as being the Gas valve isn't modulating, however it isn't the valve itself that is at issue, but the PCB. The voltage of the coil / output from the PCB was stuck at 3V, with the Max burner pressure at approx 9V, So I suppose I was lucky to even have had a luke warm shower.

The engineer is going to check through his spare parts, retrieved from decommissioned boilers to see if he has a spare PCB, else a replacement is going to cost ~ £100-150 (inc. VAT)

Not sure if I have just been unlucky, leaking auto-air vent, hole in the DHW Diaphragm and a PCB on the way out. Jury is still out as to whether the Diverter valve had stuck, or not.

Fingers crossed.

Regards

Maurice