Patterson puma 80e

[Gasguru]

Look at the manual...

Figure 33 "wax capsule head"

The front section CONTAINS the wax element...you need to remove and replace it.

Low system light is due to the port in the diverter being blocked and/or the port in the water pressure switch being blocked.
A 4mm flat blade screwdriver will clear out the ports.

 

[DADDYorCHIPS]

Okay! I’ve drained the system again! Found where the capsule is! Behind another nut on the front. Taken it out switch the washers over like the old one! Put it back together. Still the low pressure light is on. After trying
various things the low pressure light goes off. Boiler still wouldn’t fire up! Again trying various things again mainly on off wait a while try again. It’s just fired up! And for the first time in its life. The boiler Has actually stayed on! Usually it comes on for a short period goes off before it comes back on and stays on!

It’s still working. But I have noticed the low pressure light is on again. But least the boiler is working for the evening fingers crossed

I’m guessing the moment it goes off it won’t work again! Maybe it will clear itself

thanks to you both for taking the time to reply I really appreciate it

 

[ianmcd]

Probably just dirt in the low water pressure switch, they are easily cleaned, and when removed give the part where it screws into a poke with a small screwdriver, them put a dish of some sort, and crack the filling loop slightly to flush the crud out before re-fitting the switch

 

[Gasguru]

And once the ports in the diverter and pressure switch are cleared you should activate the pressure switch several times (gently poke a screwdriver through the port) and check the contact resistance...anything more than an ohm bin it.

 

[DADDYorCHIPS]

Hi guys

Low pressure light has stayed off but it seems I now have a hot water problem! It’s not getting very hot! Before I didn’t have a problem with my hot water but now I do!

simple solution this time maybe?

 

[ianmcd]

increase the flow rate to the HW, either open the inlet valve properly or check the filter

 

[DADDYorCHIPS]

I’m not sure I know how to do this! Why would it suddenly change the hot water was fine before?

 

[DADDYorCHIPS]

The pressure on the hot water seems fine btw

 

[Gasguru]

Make sure the boiler flow pipe to the radiator circuit is cool and then run the hot water. Feel the pipe say 30cm from the boiler and see if it starts to heat up.
If it does you have assembled the diverter wrongly and heat is passing to the rads. The spacer piece etc may not be properly located etc.
Also note that all 3 Puma pcbs are very poor quality...have a look at ALL the solder joints especially the connector pins for broken joints.

 

[DADDYorCHIPS]

Okay did what you said the hot water is going to the radiators! So those two black pieces I took out and mistook for the wax capsule are wrongly inserted

I’ve looked for an exploded drawing of this detail and I can’t find anything! Maybe the larger black piece is the wrong way round?

I’ve got to say this boiler is a pretty rubbish design. I’ll drain the system down again tomorrow and turn the spacer around see if this helps or if it can even be turned Round.

 

[Gasguru]

They are not spacers...AFAIR the larger part with the holes in each end shuts the water flow depending on where it has been "shuttled" too by the motor action of the wax element.
It will become obvious if you look at how the water flows through the diverter. Also make sure the inner parts of the rear diverter section are perfectly central and when you fit the front assembly back
in you keep the parts aligned ie. pins slot into the holes etc.

 

[DADDYorCHIPS]

Okay

if my memory serves me correctly. The fat part is the part that I fitted to wax capsule. I also noticed that the small narrow pin didn’t sit directly in the middle of the diverter valve it was offset. I thought this was how it should of been.
I uploaded a photo of how I didn’t fit it. The big end might of been the other way round

I’ll look tomorrow!

tbh I’m not entirely sure how this capsule works. I know it pushes something when it gets hot. But why does it have washers and I rings. And the inclosure it fits in has two holes in it. Which I’m sure I have a drip from the one side. Why even have holes there. Unless it’s to help get the capsule out?

 

[DP]

I’ve got to say this boiler is a pretty rubbish design. I’ll drain the system down again tomorrow and turn the spacer around see if this helps or if it can even be turned Round.

Sour grapes old chap. When you get to know how the appliance works, not a bad boiler. Many moons ago did makers training on this boiler
I suppose your sentiment stems from regulars holding your hand while you try to carry out repairs with parts that may not be Genuine.

It would seem the wax capsule you have fitted is not shutting down the heating port hence the hot water is sub temperature

 

[DADDYorCHIPS]

I really wished I had an exploded view of the inside of this diverter valve! Took it apart it’s in how it’s supposed to go! Just by chance I found another washer the exact same size as the bigger black part inside so I popped it on the end and inserted it. Felt a little more resistance when I popped it all back together. So connected everything up and the lockout light is on. The reset button doesn’t seem to be cancelling it.

can anyone find an exploded view of the inside of the diverter valve please? I can’t believe they left it off all the exploded drawings!

 

[Gasguru]

The problem with replacing the wax element is that you're relying on the 4 old O rings being servicable...and invariably they are worn and square section.
I've always bought new valves (often from ebay) and if you can remove the grub screws just replace the front section.
Anyway this is how is should be assembled...clean all O ring mating surfaces and grooves so they're spotless then grease all the O rings and grooves etc with silicon grease.

Diverter1

• Gasguru
• 5 Jan 2020

Potterton Puma

Fully assembled wax element..

Diverter2

• Gasguru
• 5 Jan 2020

Potterton Puma

Small pin in spacer bar must locate in rear section hole...

Diverter3

• Gasguru
• 5 Jan 2020

Potterton Puma

And now both parts fitted with "rim" of top hat section at the back to allow port to be sealed when wax element expands...

Diverter4

• Gasguru
• 5 Jan 2020

Potterton Puma

In hot water mode cold domestic water continually flows across the wax element via the 2 pipe connections on the front diverter section.
This keeps the wax element cold and therefore it's pin does not extend.
The boiler pump circulates primary water around the boiler heat exchanger (and through the diverter) helping to transfer heat energy to the domestic water pipe circuit inside.

In heating mode the boiler fires up and again the pump circulates primary water around the heat exchanger and through the diverter.
This time though the front section of the diverter containing the wax element gradually heats up through conduction from the rear section (containing heated primary water).
The wax in the element expands pushing the pin out and this forces the top hat section, spacer pin and rear section back towards the wall opening up the radiator circuit.
Inside the top hat section you'll also find another spring loaded mechanism to take up excessive pin movement and protecting the wax element from excessive pressure.

The Puma is a pile of junk...it has several design flaws. Rumours were that Potterton had so many warranty calls they ended up being bought out by Baxi to save them.
At one time it contributed a significant income to gas repair engineers