Glow worm 24ci only produces warm water

[rip]

Hi.

I have a Glow worm 24ci which is about 4 years old ish. Recently the flame would cut out if running hot hot water ((eg, shower). (I got completeley fed up of doing the hokey cokey in the shower). I spoke to a plumber who told me to up the pressure on the central heating side, and I did, and this problem went away. (now 1.5 bar)

But now the water just won't get hot enough. It used to be scalding (when running water at slower speeds), but now it stays at a constant temperature, just not hot enough, no matter the speed of the flow. Flame stays lit.

I have changed the water flow sensor (expecting no change) and there was no change. I am tempting to change the heat exchange for the DHW.

The heating is still fine. Can anybody please give some advice, before forking out loads of cash.
Thank you.

 

[Vaillant Engineer]

Hi, first thing to do is check the diverter valve is not passing I.E does the rads get hot when the bath is running that could be the cause of low temperature on water only (Boilers heating the house as well as the water) If the DHW heat exchanger is restricted by scale then the flow to taps would be poor alternatively if heat exchanger is blocked then boiler would fire and then go out and keep cycling on and off or else the DHW thermistor could be at fault.

For expert solution call manufacturer (Gloworm) on 01773 828100 and get fixed price call out includes parts and labour for around £200 and includes 6 months gauruntee.

 

[rip]

Thank you for your prompt reply.

The pipe work for the radiators are stone cold when running hot water for a while, (checked directly from the boiler).

The actual flow of the water is still very fast, if I want it to be. But to get any temperature of water, I need to restrict the flow alot, only to receive luke warm water at any speeds, but the boiler stays lit, with a high flame.

Could you possibly tell me a little more about this DHW thermistor?

I have access to a temperature gauge with the laser on it. I am going to take readings of the DHW heat exchange to see if there are any cold spots. If there is, then I will change the heat exchange, if not, I will use the number you supplied for me. Thank you.

 

[Agile]

I think that Vaillant now own Glow-Worm !!!

An IR thermometer is of no use in measuring boiler temperatures. You need a contact thermometer.

The differential across the primary HE should be no more than about 20°C. If its much more then the secondary HE is likely to be blocked which is very common if the system has not been properly cleaned.

You need a digital test meter to measure the resistance of the sensor. Cold it probably should be 10K but refer to the MI for confirmation of this value.

Tony

 

[gasgeezer]

Before you change any parts check the gas working pressure and burner pressure.Had a similar prob. turned out to be faulty governor on the meter.Found it on third visit previous visits all ok.Transco turned up as i was leaving said no fault, yet only 10mb when i checked it got them to change gov not been a prob since, meter was only 3 months old

 

[Agile]

Gasgeezer, as this is a user how do you expect him to be competent to check gas pressures or even have a manometer?

I consider it irresponsible to suggest that anyone does anything which could be hazardous.

Tony

 

[plumbnuts]

I also think that it's a gas supply fault either at the meter or undersized gas supply to the boiler and suggest that you get a CORGI registered engineer to check. This may be cheaper in the long run as changing parts unnecessarily can become expensive. Good luck

 

[GeoffCoates]

I have the same problem, one bloke advised me its the heat exchanger and another bloke said 'Powerflush' so had that done on 13th Feb.

Still no hot water but heating is great now. I have booked a BG engineer to come and see what he can do.

Will keep you posted.

 

[45yearsagasman]

I'll lay a tenner that it'll be the plate heat exch blocked on the primary side.
A power flush will not clear that part of the boiler. It needs to be removed and cleaned.

 

[geoff1951]

I think you are right to 45yeargasman. I will pass that onto the B.G. engineer on 24th.

BTW, I don't bet on certainties - lol

regards
Geoff