Radiators not heating up.

[MisterFish]

So, a few days on. That doesn't seem to have made a great deal of difference.

I can turn rads on and off and push though to others but I only seem to be able to heat up two or three at a time.

I've not spent a lot of time watching the boiler until recently. The gas kicks in, the temp goes up to around 70-75, the send pipe gets hot, it runs fopr a few minutes like that then the boiler knocks off until the temp gets back down to about 45 then it all starts again. The return pipe never gets past tepid. That all normal?

The other thing that has happened now a couple of times is that the water light comes on when the water is drawn and then won't go off again when the water stops. Turning off the boiler for a couple of minutes resets the system and away we go, (the reset selection on the selector switch does nothing).

EDIT: I now have the two rads cranked up in the living room (one at the front of the system and one at the end) the thermostat turned up and pretty much everything else turned off. (The bathroom won't turn off but everything else).

The Send from the boiler is still getting mad hot and the return hardly warming at all. The living room rads are warm to hotish.

Hmmm.

 

[FlyingFish]

With the white cover removed, (not the combustion cover) grab the flow pipe which is on the left (copper) with one hand, and then grab the return pipe on the right next to the pump with your other hand.

Put the heating on and wait for the temperature to increase upto 70C. Try not to burn yourself! Is the return pipe next to the pump (going up into the combustion chamber) just as cold as the return is under the boiler or is it nearly as hot as the 70C flow pipe?

Mick

 

[MisterFish]

I think I understood what you meant. Did you mean the two pipes, A and B in the following image?

//www.diynot.com/diy/media/img_2163.99249/

If so, they are both at a similar (high) temperature.

 

[FlyingFish]

On the left and right heating isolation valves, under the boiler, far left and far right. Remove the small pozi screws holding the black plastic levers to the spindle. Once removed, check that the flats of each spindle are inline with the flow of water, so fully open is flats running front to back.

This is to prove both valves are fully open.

 

[FlyingFish]

Once that is proved you need to check that black motor under label A in your photo.
To do this turn the boiler heating temp to minimum, then unclip, pull up, the hall effect sensor the one that lights red when water is drawn. It's to the left of the pump. Just rest to the side.
Then remove the black clip under the black motor, that pushes through the brass nut.
Lift off the motor, (cable still connected) and look at the brass pin on its underside. Open a hot tap ( the boiler won't do hot water). Leave it running.
Put the heating on.
Is the brass pin fully out or can you push it down its hole?

 

[MisterFish]

Once again, to check I'm looking at the right thing:

//www.diynot.com/diy/media/img_2162_2.99250/

1 and 2 are alligned. On number 3, someone, presumably the installer has stripped the cross on the head. I can't get it open.

When I turn it, and when it stops in the open position it feels like it's turning a valve rather than just a handle. Also it is the send and the send pipe is getting mighty hot beyond the valve, which would, I think, indicate that it is open.

 

[MisterFish]

Okay, done all of that.

Firstly, when I approached the motor I noticed that there has been some leakage from there. A drop or so of water and evidence of corrosion.

//www.diynot.com/diy/media/img_0864_a.99253/

with the hall sensor off, I removed the motor. The neck of the motor was pretty corroded and rusty.

//www.diynot.com/diy/media/img_0865.99254/

As was the socket beneath.

//www.diynot.com/diy/media/img_0866.99255/
//www.diynot.com/diy/media/img_0866.99255/
Bad photo, difficult place to photograph.

With the water switched on and the heating running at low temp the pin in the socket was out about 5 mm (hard to tell, measuring by feel in a hole) and was almost impossible to push back. Trying really hard I moved it a little. Initially I thought you meant the underside of the motor but there appeared to be no pin there.

I did not feel the pin move in or out when starting or stopping the water it simply remained in place.

Of course I'm working in the dark a little here, I don't know what any of these things should do or how badly corroded these bits normally are anyway.

 

[MisterFish]

Post removed

 

[FlyingFish]

Ok, you need a diverter repair kit, and a new motor. The motor has a brass pin that pushes down onto the steel pin in the brass head of the water diverter valve. A spring within the diverter valve then pushes the steel pin back out when the motor retracts its brass pin.

What's most likely happening is the corrosion on the steel pin has limited it's movement and is obviously leaking (into the motor, which could also be affected). With limited/poor movement heat is probably not being fully diverted into the heating circuit and is actually passing straight through the stainless dhw heat exchanger, felt by the hot return pipe (B) .

Mick

 

[MisterFish]

So again for clarity, (and remembering that I am a beginner), I need to repair/replace the Diverter Valve - Motor Unit & Assembly as outlined on page 40 (article 13.20) of the Boiler manual.

http://www.baxi.co.uk/documents/7219665-01_Duotec_HE_A_ErP_Install.pdf

Is that correct?

Sorry if I sound stupid, but I have never done this before.

 

[FlyingFish]

Half right
The motor is plug and play, the hydraulic part is a cartridge that unscrews and gets replaced baxi part: 7656807

Whether you feel competent to do this is up to you. Buy the genuine baxi part, and not an eBay copy. It will come with fitting instructions.

 

[MisterFish]

I'm going to have a crack at it. If I need to get someone in afterwards to put right my screw up then so be it.

I was unable to get the parts today, I will live with the spotty system till Moday and then get on it.

I'll let you know how it goes. Thanks.

 

[FlyingFish]

Have fun, take your time. Oh and when screwing in the new cartridge try not to crush the round of the brass cartridge if using large pliers. And take note of leaving the bottom nut loose while screwing down the cartridge. If you don't, a hydraulic 'lock' could damage the new part.

 

[MisterFish]

Parts ordered yesterday, arrived today.

Very clear instructions with the part. The job took about 15 minutes. The heating seems to be working normally again.

Thanks FlyingFish. Help much appreciated.

 

[Steelmasons]

I detect a Jekyll and Hyde going on between the two of you......sorry one of you.