Gloworm compact 80e combi boiler- warm water problem!!

[heinzy]

Hi,

I hope someone experience in combi boilers can help...........

When i turn on the hot tap, it stays warm for an age, and may eventually rise to an acceptable temp for a shower etc. There seems to be a trick though... If i reduce the flow considerably, the water will get hot, and if I then increase the flow to normal, it all seems to be OK for a time, then it will go luke warm again.

Observations:

- Central heating is fine

- The gas 'flames' look steady and do not modulate in height at any point

- A firm has diagnosed the gas control valve saying the pressure one side was different than the other side??

Can anyone confirm that this valve may be causing the fault?? - My reservation is that the Central heating is OK, so why could it be the valve

Many thanks for some expertise here

[Andrew Gabriel]

I don't know that boiler, but most boilers use a combined gas valve and pressure reducing valve, and hence you would expect the pressure to be different. However, the symptoms you describe do match a lack of power into the primary circuit.

[<me9]

That's because the water is already hot in the pipe, and when the next bit (not fiully heated cos it has passed more quickly through the boiler) gets there it is cooler.

Someone is trying to extract the readys for an inadequate repair.

[John]

You should actually measure the flow rate not just look at it and guess. To do this either buy a wier gauge or time how long it takes to fill a 9 litre bucket (1 minute would be about right which is the expected flow rate or thereabouts for a 35 degree temperature rise)

Again although looking can give an idea you really need a manometer on the burner pressure test point for sensible detection.

Stupid bastards! of course the pressure is different on either side of the valve. One function of the valve is to take gas at meter governor pressure (around 21 millibar) and regulate its flow into the boiler by controlling the pressure into the burner (varies according to the modulation but significantly less than meter pressure). Don't allow these useless clowns near your boiler again.

One of the problems sometimes found with the Glow Worm is system muck causing obstruction of the diverter valve mechanism and instead of all the heat from the burner going to the water some of it leaks out into the heating pipework. An easy test is to close one of the heating pipe isolating valves (underneath the boiler) while running the hot water so nothing can escape to the radiators. If the performance improves you have found the culprit. Do not leave it in this condition after the monitored test though!

If you find the problem but feel you aren't up to competence to do the repair yourself get a decent guy in.

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[heinzy]

Thanks for all you replys - its been very informative.