Hot water issues.

[fraker]

I have a problem that I would like a little advice on.

First of all the system (Such as it is)

We have a Potterton Flamingo RS50S (11.7 to 14.7 kW) this serves the hot water and heating.
I believe Noah had a similar boiler.

This is supported by a Grasslin QE2 controller (Less than six months old.) A Danfoss HSA3 diverter valve and a Grundfos Alpha2L circulation pump set to constant speed one.
Both the pump and the diverter have been replaced this week by myself in an attempt to resolve this issue myself, however, so far it continues.

The radiators have been bled as has the pump (self bleeding) and the pipework using the bleed valve near the pump.

The problem is this:

The central heating works just fine. All of the radiators get good and hot (perhaps too hot?) and the system responds to both the room thermostat and the controller settings.
The hot water also gets good and hot and responds to system commands BUT, the issue is that about an hour after the hot water is turned on, the pipework makes a god awful noise and vents very hot water and steam up into the feed and expansion tank.

So, what I would like to know is, what could be causing this and how can I remedy the situation?

Many thanks in advance.
Bill.

 

[Cpplumber]

Please ignore last...realised you gave the model.

 

[Cpplumber]

When this occurs, is it at roughy the same time it is programmed to go off?

 

[fraker]

Cpplumber, thank you for your response.

Sadly, no. It bears no relation to how the programmer is set.

Further investigation suggests that it may be the thermostat on the boiler itself that is causing the issue as the radiators get too hot to touch and there seems to be an increase in pipe noise the longer the heating is on.

My previous comment about it taking about an hour was wrong. Upon switching on the water heating it starts venting into the F&E tank within 20 to 30 minutes.

Bill.

 

[45yearsagasman]

It's either a failed boiler stat, or a pumping over problem. From what you say, I would tend towards the boiler stat ( too hot to touch ). Set the boiler stat to minimum and check the flow temp. This will require an instrument rather than your hand to be accurate. The stat can be changed without interfering with any gas seals.

 

[fraker]

Pete.
Many thanks for your reply.

I have no qualifications in plumbing or heating, I am merely a DIY'er so I think, from what you have said, I shall shut the system down for now and get someone in who knows what they are doing as I have reached the limits of my abilities. I don't like messing with anything related to gas. As my father always said, "I can't feel it or see it... Until it's too late."

Besides, all the noise and very hot water in a plastic F&E tank makes me a little nervous having heard and read horror stories of tank rupture/deformation.

Would anyone on here happen to know a reputable heating engineer in the Dagenham area?

Edited due to fingers outrunning brain (Again)