Help. No hot water but boiler is firing!

[andycharger]

Hello ladies and gents,
For a couple of weeks ive been looking for various solutions to our hot water problem at home.

We have a Grant Outdoor Mk II oil fired combi boiler. I dont know if that is a good thing or a bad thing.

We suffer pressure problems anyway and always have in the central heating and im forever having to repressurise the system.

However we have no hot water at all at present and with 2 small children is a real issue!

I have replaced the Expansion Vessel as it appreared the membrane was persished ( the inflation valve dripped with water)

We have taken off the Heat exchanger and descaled it over night to see if that was blocked. It fizzed like mad and seem to be active at removing the limescale if there was any in there. We put it back on and still nothing.

I know this much... When the boiler fires up, (and it is firing up!) there is a pipe that feeds the Heat exchanger from the boiler. Its red hot when it leaves the boiler but when it enter the heat exchanger it appears to be cold.

I can think it is one of 2 issues.
1) the 3 Way valve is not working at all/correctly?

2) the heat exchanger is blocked.

Ive pretty much ruled point out as i can blow through any of the openings on the exchanger and get air coming out of the corresponding hole on the other side.

Could it be anything else and what do you all think the issue could be?

Thanks for looking

Andy

 

[mark6266]

Best Call a Oftec Heating engineer . Grant boilers are very good inho. Oftec have a list of heating engineers on their web site .

 

[andycharger]

I have an engineer coming out in the morning that has been over before. Im going to post back once he has been with the outcome in case it helps others with a similar problem.

Any suggestions prior to then are appreciated as to what it may be.

 

[andycharger]

Hi guys and gals,
Right, my boiler man came out to look at the boiler and confirmed my issues. Its the heat exchanger. This is the 2nd one we have replaced in the 3 years we have lived here.
The problem was first thought to be the pump that pumps the water around. However it was tested on the heating and worked fine.

It appears that despite my descaling of the heat exchanger, it does not descale enough to be practical. Therefore im replacing it with a new one. Before I do, im adding a new chemical based water softener to the pipe that supplies the Hot water. Im hoping this with remove as much scale as possible and will just require me to buy tablets every few months. Im also hoping it stops this exchanger from seizing up!
While that is being done im also replacing the Water Diaphragm in the 3 way valve in case there is any perishing.
At the moment the high end shut off is kicking in as there water is unable to go anywhere. Im also going to check the high end thermostat!

Anyway, this is all being fitted tomorrow (parts have cost me £140 to source) and will report back when its all fixed.