Ariston eurocombi A/23 MFFI help!

wacomuk · 7 Oct 2007

I am having problems with my hot water. The water was running warm cold warm cold never hot

My 1st thoughts where clogged heat exchanger so i power flushed it with limescale & sludge remover (hot water side and rads)
The water now runs warm MAD HOT! warm MAD HOT! etc
I have also fitted a new temp sensor but this made no difference

Its like the boiler get to temp then shuts down (not over heated) then fires back up again so on and so on

gas4you · 7 Oct 2007

Whats the flow rate out of the hot tap, it should be about 9-10 litres /min with this boiler to get a 35C temp rise.

wacomuk · 7 Oct 2007

just tested. 10L took 58 seconds. water temp was luke warm

gas4you · 7 Oct 2007

Doesn't sound like a blockage then. When you run a hot tap does the ch flow pipe get hot?

DP · 7 Oct 2007

Looks like a bit of tempering might have taken place. Also gas line might be suspect if boiler cannot deliver specified quantity of water at the tap at 35°C.

For this temperature rise, when water in is colder, temperature sensor often stays out of the picture.

wacomuk · 7 Oct 2007

the central heating flow pipe doesn't change temp when hot tap is run

if i lower the flow rate to 5L in 2 mins the water temp stays steady and hot

gas4you · 7 Oct 2007

I think you need a corgi to check the gas rate and burner pressure/co2 content as a basic first before you go any further.

Agile · 7 Oct 2007

Always goes a little quiet when a suggestion involving spending money is mentioned!

Tony

wacomuk · 8 Oct 2007

thanks for all the help. when you say corgi need to come out do you mean a heating engineer who is corgi registered or someone from corgi?

Gasguru · 8 Oct 2007

Have you checked the flow/return temperaturesa across the plate exchanger?. I'd remove the plate and check it.

With the boiler completely COLD open a hot tap fully. Put your hands across the flow/return pipes inside the boiler. Often a large difference in temperature and the boiler modulating down indicates the plate is blocked.

wacomuk · 8 Oct 2007

Gasguru said:
Have you checked the flow/return temperaturesa across the plate exchanger?. I'd remove the plate and check it.

With the boiler completely COLD open a hot tap fully. Put your hands across the flow/return pipes inside the boiler. Often a large difference in temperature and the boiler modulating down indicates the plate is blocked.

i will give this a try tomorrow

Agile · 8 Oct 2007

The same symptoms can occur when the pump is not operating correctly or there is a blockage in the boiler apart from the plate HE.

Tony

wacomuk · 8 Oct 2007

if the boiler was blocked would this affect the rads as well as the hot water? The rads have always worked perfectly.
when i flushed the hot water side it was bringing out black sluddgy stuff,
i flushed the system 3 times 1hour each time, could more flushing help?

Gasguru · 8 Oct 2007

A blocked plate would have no effect on the radiators.

Remove the plate to clean it unless you have access to a powerflushing machine and a pump adapter where you can reverse flush the plate, however this method risks contaminating the primary heat exchanger.

Agile · 8 Oct 2007

wacomuk said:
I am having problems with my hot water. The water was running warm cold warm cold never hot My 1st thoughts where clogged heat exchanger so i power flushed it with limescale & sludge remover

When I first read that I assumed you had a power flushing pump and knew what chemicals to use. Now I have my doubts!

How did you connect the power flushing pump to the plate HE ???

What chemicals did you use?

It is probably still the plate blocked unless it was PROPERLY cleaned.

the plate HE has NOTHING to do with the heating! Its for the HOT WATER

Tony

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Ariston eurocombi A/23 MFFI help!

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