combi boiler hot water problem

[maxmark]

hello,i have a ariston eurocombi sx20 mffice the problem is when i turn a hot tap on when it starts to get hot it cuts off for about 40 secs then comes on again and repeats same with ch thermostats are on full and seem to be working when lowerd can somone help

 

[NScott1969]

I have the same problem with an Ariston Microgenus 27. I have changed both thermocouples but this made no difference. If you find someone who knows why this is happening please let me know.

Best Regards,

Nathan.

 

[oilman]

Both of you, have you always this problem?

How old was the boiler when it started?

What is the flow rate from the hot tap?

What is the flow rate from the cold tap?

(Hint: use a bucket and a stopwatch)

It is possible the heat exchanger needs descaling/replacing, and the water cannot take the heat away fast enough, so the stats in the boiler take over.

 

[NScott1969]

This problem has been occurring over the last 6 months, the boiler is 2 years old. I put flushing fluid in for a while and I think this helped a little (can not be entirely sure).

Flow rate from hot tap = 1.5 ltr / sec
Flow rate from cold tap = 2.5 ltr / sec
Both measured at kitchen sink (approx with 1 ltr measuring jar)

Best Regards,

Nathan.

 

[oilman]

Flow rate from hot tap = 1.5 ltr / sec
Flow rate from cold tap = 2.5 ltr / sec
Both measured at kitchen sink (approx with 1 ltr measuring jar)

WOW!!!!!!!!! thats 90 litres a minute from the hot tap
Can you really fill ten 2 gallon buckets in a minute from the hot tap, and 15 of them from the cold tap?

 

[masona]

Can you really fill ten 2 gallon buckets in a minute from the hot tap, and 15 of them from the cold tap?

Is the water pressure enough for a combi ?

They must've plumb it into the fire mains

 

[supersparks]

BLODY ELL!!! how big are trhe damn taps and pipework?!!!! you have fire hydrents as taps mate!!!??!?!??!

be quite interesting to see this setup
ive herd of people having strange things, but this takes the mick so you have a boiler in your home that was ment to supply a street? fair play

 

[supersparks]

btw, forgot to ask, how is it for filling a bath?

 

[NScott1969]

Ah yes, got my numbers wrong there sorry.

Hot tap: just under 1/4 ltr / sec (not very hot obviously).
Cold tap about 1/2 ltr / sec.

Sorry,

Nathan.

 

[oilman]

Nathan, if you are using a 1 litre jug to measure this, I think you should be using a bucket and timing that. I think the 1 litre jug measurements will not be accurate, and it could make a difference. You need a measuring time of at least 15 secs.

 

[maxmark]

I have the same problem with an Ariston Microgenus 27. I have changed both thermocouples but this made no difference. If you find someone who knows why this is happening please let me know.

Best Regards,

Nathan.

hello i have sorted my boiler out i took off the chamber seal plate a it worked fine so i took it that there was a problem with air pressure,i changed the air pressure switch and had no problems with the boiler since .

mark

 

[ChrisR]

That's a completely different problem Mark.

 

[NScott1969]

I have measured more accurately from the bath this time 10.5 ltr container:
Hot water = 0.22 ltr/sec
Cold water = 0.32 ltr/sec

Regards,
Nathan.

 

[ChrisR]

OKay. Problem is usuallya bit of sludge build up on the primary side of the secondary heat exchanger, or scale on the secondary side if you're in a hard water area. Are you?

Either is cleanable of course.

 

[oilman]

ChrisR, I thought that with 12 l/min the exchanger would have been ok and though it's down a bit on the cold flow of 18 l/min it's not too bad. Will this flow rate cause the boiler to short cycle delivering hot water?