Potterton Puma 100e -start of winter- HW fine CH not working

[adj]

Thanks ChrisR

If the HW works, none of pressure switch, air vent etc could be a problem.

Thanks, Chris. I'd be barking up the wrong tree for hours then.

The front end of the DV needs to be warm for the CH to work - you can help it.

I tried giving it a quick blast with a lighter. No noticeable effect.

It should get warm when the boiler runs and there's no tap HW flowing.

The back of the diverter gets hot but the front part, where the wax valve is located, stays cold.

Does the pipe out of the back of the DV get hot (ch flow).

Yes, the back of the diverter gets hot. The pump also gets hot. The pipe out of the back of the diverter gets warm but not hot. This is the CH out pipe I think. It gets cooler as it goes and is cold before it gets to floor level. I think the water above it is heating it but the water itself is not flowing.

Could be your pump's sludged up or going slow.

I thought I had ruled this out earlier but would that explain why the pipe goes from warm to cold as it gets further from the boiler?

 

[adj]

I just noticed there's some carbon on one of the relay switches on the PCB.

http://www.7seals.co.uk/assets/images/puma 100e/CRW_1368g.jpg

Is that likely to be the source of the problem?

Andy

 

[Agile]

You have already stated what the problem is! The front of the diverter valve is cold !!!

Again I will ask you to turn off the cold water supply into the boiler. On its own this should allow the front to heat up in 2-3 minutes.

This time after turning the water off please unscrew the two 15 mm connections where the cold water flows past the wax stat. With the pipes unscrewed the CH will then work after it has warmed up.

However I dont expect you will get that far because when you unscrew the two connections you may find the water is not really turned off.

WARNING: before unscrewing anything turn off the power and put a plastic sheet over the electronics.

Tony

 

[ChrisR]

carbon on one of the relay s on the PCB

No that's the fan relay. They all do it sir.

When you turn the cold water off you might find it drips slightly. Never mind, they almost all do that too. It stops quite soon.

 

[adj]

Hi Tony

Thanks for bearing with me.

I turned off the mains supply to boiler. The only way I could see of doing this was to shut off the main stopcock to the house.

http://www.7seals.co.uk/assets/images/puma 100e/CRW_1370-01gred.jpg
http://www.7seals.co.uk/assets/images/puma 100e/CRW_5838-01g.jpg


I really don’t think there was water getting into the boiler. With this shut the boiler is no different. There doesn’t seem to me to be any other tap or obvious way to stop the cold feed to the boiler.

I was going to unscrew the two 15mm connections but I thought I’d better double check as I wasn’t certain I picked you up right. I had a picture of me being soaked and then electrocuted which is not a good way to end the year

Do you mean to disconnect the arrowed connections and then fire up the boiler? http://www.7seals.co.uk/assets/images/puma 100e/CRW_1352-01g3red.jpg

Reading between the lines it looks to me like you still suspect the diverter. Should the CH run with the water off at the main stopcock? If I do unscrew the 15mm connectors wouldn’t I have to drain the boiler first? If I did would it be worthwhile undoing the 2 hex nuts too to see if there is a sticky mechanism in the wax valve. (I take I the wax stat is the wax valve).

Thanks again for your time.

Andy

 

[Agile]

Turn on the hot tap first to relieve pressure and turn off the water and then disconnect the two yellow arrowed nuts and try the CH. .

Dont do anything else, just what I have asked. Let me do the thinking.

Please dont take much longer as I dont know that I have a long enough attention span.

I am creating a situation whereby the front of the diverter has to get hot and allow the CH to work!!!

I am surprised you are taking so long.

Tony

 

[adj]

Hi Tony

Happy New Year.

Thanks for all your help. I am not attempting to try your patience.

I did as you said.

When I swithched on the CH, the boiler fired at first. The tops of the radiators in all rooms got slightly warm. After a few seconds the boiler switched itself off. The boiler continued to switch on after every ten minutes or so and only stayed on for a few seconds each time. The radiators are basically cold (very slightly warm at the top). The diverter is also cold front and back. The pump is warm at all times. The CH out and return pipes are both cold.

Andy

 

[baxpoti]

An observation;
Looking at your photos, I noticed your dhw micro switch is not set correctly, its screwed in too far, there should be a 5mm gap measured from the screw thread start (on microswitch) to the brass of the diaphragm housing.
There doesn't appear to be any gap on yours at all.
It could be camera angle or its been replaced and not set correctly.

In this scenario dhw has priority and no c/h.

Only problem with this theory is the red light is not illuminated on the modulation board.

 

[adj]

Hi Baxpoti

You've got sharp eyes

I checked and the gap is less than 1mm. The manual says 5.5 mm +/- 0.5

Should I readjust the gap or continue to look elsewhere for the problem?

The CH worked fine for 6 months or so last year and I am certain that no-one has touched the microswitch since then.

I'm glad the photos can show that kind of thing. I'll try and leave them up as long as possible in case they help other people.

Andy

 

[baxpoti]

Remove the switch and turn the plunger end 180* (they wear on one side)
Replace at correct setting
If dhw not working now, you'll need to replace the worn diaphragm

 

[Agile]

You can easily test the DHW switch is not on by temporarily disconnecting one wire but as the red light is not illuminated I dont expect it is made. I dont know what the 5.5 mm is meant to refer to as I always set the air gap to 1 mm and this seems about right.

The rear part of the diverter should be hot on CH. This heat is provided by the main HE and circulated by the pump.

The boiler will still give DHW even if the pump is failed. Are you quite sure the pump is turning on CH and the impeller is still attached. The pump being warm is not relevant. The black hex knob should spin with the shaft when it is unscrewed anticlockwise and pulled forward.

Tony

 

[ChrisR]

adj, if we say that you thought of doing what Tony says first, then would you actually do it?

 

[adj]

Hi Guys

Thanks a lot for your continuing help.

I guess my last post to in reply to Tony wasn't clear. I did do exactly what he suggested and removed the two yellow arrowed connections after turning off the water. (The only reason I delayed was because I was slow to understand what he was saying).

I have also removed, rotated, regaped and replaced the microswitch. The HW is still fine and the CH is the same as before.

(The 5.5mm includes the airgap and the locknut.
http://www.7seals.co.uk/assets/images/puma 100e/microswitch.gif)

The back of the diverter did get hot at first (when the boiler fired). It did not stay hot though, unlike the pump, so that's why I wrote what I did above.

I unscrewed the octagonal knob and the pump still continues to rotate it anticlockwise.

Andy

 

[Agile]

The boiler will still give DHW even if the pump is failed. Are you quite sure the pump is turning on CH and the impeller is still attached. The pump being warm is not relevant. The black hex knob should spin with the shaft when it is unscrewed anticlockwise and pulled forward.

Tony

 

[adj]

Hi Tony

Thanks for the quick reply. I'm not sure what the impeller is so I don't know if it's still attached.

How could I check that?

Andy