Hi I am hoping someone can explain what the problem with my Condensing-combi boiler is. The boiler has been installed for about 3 years. Recently the hot water flow has a problem. If the tap is turned on for more than half a turn the water runs very cool. This makes the shower unusable and the bath takes an age to fill. The problem has become worse over the past few weeks. Can anyone offer me advice as to the cause of the problem or aprox how much it will cost to repair?
Thanks Richie
Are you in a hard water area? It could be the plate heat exchanger is getting badly scaled. What make/model of boiler is it?
Which boiler is it?
Have you tried running DHW demand without any heating on? If so, does the burner ignite?
Angus
If this problem has suddenly come on then I'd suspect the modulator is not going to full rate? As always with boiler questions there are a selection of manufacturers who make a selection of models for info in this area can help a lot.
Hi yes I have tried running the DHW without the heating on. The flame ignites and the water runs hot but as soon as I increase the demand ie turn a tap on more than a quater turn it cools off
the boiler is an ISAR 30HE
Thanks very much for the response and the links I will have a look.
What is the fan doing while you run the tap? - as you up the demand the fan should run up to full speed.
The Ideal Isar. This has a small store of hot water. What flow are you getting? The boiler should be more or less flat out with 10 seconds or so of you running a tap.
This problem is getting stranger by the day. When I run the DHW the radiators start to heat up!! So as far as I can tell, yes the boiler is flat out but seems to be sending most of the energy to the central heating! Does this make any sense???!
The flow is fine but if I turn the tap on more than a quater of a turn the water starts to run cold. My wife noticed also that the radiators get hot with the hot DHW tap running, that is with the central heating turned off at the timer! I can only maintain a hot water flow on the DHW with the tap open slightly. It seems as if the Boiler cannot cope with a resonable flow rate.
Haven't worked on an ISAR for a couple of years, but most likely your diverter valve is jammed, the DHW demand is lighting the boiler but the results are sent down the heating circuit. You may be able to dismantle it and free it off, but I'd plump for a new one.
Angus
Thanks very much for that Angus. Sounds spot on to me. I will let you know how I get on.
Yup, stuck diversion valve.
With the ISAR you can remove the body of the actuator from the valve body - it is a rectangular box at the bottom left of the unit. IIRC it is a bayonet type of fixing so you push it in a little and give it a partial turn. You can then remove the actuator from the actual valve. The valve body has a peg that sticks out. You should be able to push this in with thumb pressure - release it and it ought to spring out again. That should let you see if it is the wet part of the valve that has seized or if it is a problem with the actuator.
(you can download the install manual from Ideal web site - but I can't seem to reach it at the moment. When you get it, the diversion valve removal prcedure is on frame 60 (Page 38))
Sorted thanks Angus. You were right, It was very tight. I managed to free it a little but couldnt fully dismantle the unit to get the 'piston' out. I will be ordering a new unit but in the meantime I have put it back in and seen some improvement. Thanks again for taking the time to help me out.
Richie
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