Potterton Powermax 150 HE Expansion Vessel

[magicmanalex]

Morning Folks,

Last week, I managed to get a radiator working that I believe has never worked since the house was built in 2007. Massive thank you to Dalalio on this forum who helped me with the problem.

I've read the FAQ on re-pressurising and here's my plan for today. Would really appreciate it if someone wouldn't mind double-checking it.

Background:

• Potterton Powermax HE 150 boiler. 7 years old. Losing pressure and needs topping up via filling loop on daily basis. 11 radiators of varying size (some very small!). All radiators and hot water working perfectly though.
  
  
• Believe boiler has never been serviced. Will get it serviced annually once fault is rectified.
  
  
• (Water hardness in area is ‘very hard’).
  
  
• Two VERY slow leaks from upstairs rads (son's bedroom bleed nipple and office TRV).

Plan for today:

1. Turn off Central Heating. Allow to cool. Power off boiler at mains.
   
   
2. Turn off both valves on kitchen rad (no drain cock in house). Drain rad and attach garden hose to TRV valve. Run hose into garden drain.
   
   
3. Fully open kitchen TRV valve and drain system fully. Open a few upstairs bleed valves to allow air in and drain for about an hour until system empty.
   
   
4. Whilst empty, repair/replace upstairs leaking TRV. Remove and patch up son’s radiator bleed nipple valve with PTFE tape.
   
   
5. Pump up boiler’s internal expansion vessel to 1.0 bar (is it unimportant if radiator bleed valves are open or closed because system should now be completely empty of water and therefore no pressure?). If water comes out of Schraeder valve, order a replacement expansion vessel - no point wasting Fernox at this stage. Book gas-safe engineer to fit.
   
   
6. If no water coming out of Schraeder valve, pour 1 litre of Fernox F3 into system via son’s radiator using funnel and re-insert PTFE’d bleed valve. Refit kitchen radiator.
   
   
7. Close all opened bleed nipple valves using radiator key. Fill system to 1.0 bar. Bleed downstairs rads. Bleed upstairs rads. Repeat until gauge shows 1.5 bar and no air in rads.
   
   
8. Power on boiler. Turn on central heating and let Fernox F3 do its thing for one week (and hope pressure stays reasonably stable). If son’s 1/2-inch valve leaks during this time, order a new valve.
   
   
9. One week later, assuming all OK, repeat process to drain system and remove Fernox F3. Once empty (and whilst hose is running into back garden sewer) add water via filling loop to flush system. Leave water running until all Fernox flushed out and water running clear.
   
   
10. Add Fernox F1 inhibitor. Top up system again.

Apologies for the length of this. The only thing I haven't mentioned is the PRV. I now know not to drain anything via the PRV in case it gets clogged up with debris. Very hard water area so probably already is. Have seen a YouTube video on how to clean them. I'm a reasonably competent DIY-er, but is the PRV something I should not attempt to replace or clean myself?

Thanks in advance! Hope you all have a great weekend!

 

[Agile]

I have not read all that as I have paid work to concentrate on.

But why on earth don't you have your boiler serviced?

Tony

 

[magicmanalex]

We only moved in 18 months ago. We thought the house had been well cared-for, but have found more and more things wrong with the place. I don't BELIEVE the boiler has ever been serviced. I could be wrong though. No service record and Potterton don't have it registered.

We will service it, but Potterton have quoted £350 for a fixed price repair plus £147 to service it once repaired.

If the expansion vessel just needs inflating, we'll have wasted £350. I want to repair the leaky rads and flush it through with Fernox and clear it out before any repairs take place.

 

[Agile]

I always recommend that all appliances are serviced whenever anyone buys a property.

As you will agree boiler servicing is recommended every 12 months and most engineers will say particularly on that model.

Any engineer will be happy to come and check your expansion vessel for well less that £100. Or as you plan to check it yourself. But before depressurising the system, empty all remaining air from the EXV as that will show how much water there is in any. A small amount of water may not mean that it is failed.

In your case waiting 18 months does not indicate much of an inclination to get the boiler serviced regularly.

Tony

 

[magicmanalex]

OK thanks for the reply.

CH has been off for a couple of hours.

Current pressure is 1.4 bar. So power off boiler and empty internal expansion vessel via Schraeder valve before doing anything else?

When the air stops coming out of the Schraeder valve, the boiler's pressure gauge will then tell me how much water pressure is in the system before draining?

 

[andytw]

I would fit a new schraeder valve regardless.

 

[magicmanalex]

Cheers Andy - will pick a couple up.

 

[magicmanalex]

OK,

Took all of the covers off today, as per Potterton service manual, to look inside.

It is now clear that this boiler has never been worked on or serviced since installation eight years ago. The 'roof' panel was covered in plaster rubble and dust from where the two flues are routed into the attic. I carefully hoovered it off before removal and noticed that a lot of dust was sitting on the top of the internals below. Gently hoovered that off too.

I'm absolutely disgusted that in this day and age building and installation procedures are that sloppy. It beggars belief. My girlfriend moved into the house a couple of months before I did and told me today that she had to hoover rubble out of the boiler's cupboard when she first arrived. The installers (and previous owners) should be ashamed of themselves.

Anyway - rant over....

Water came straight out of the expansion vessel Schraeder valve so I'll order a new vessel and PRV. The parts are only about £100 online and owing to the boiler's lack of maintenance, I'm willing to just get a new EV rather than renew Schraeder valves etc.

I assume there MUST be gunk and rust in the circuit, despite no cold spots on any radiators (and the one rad I flushed with a hose was absolutely clean).

Would like to have added the litre of Fernox F3 before replacing the parts in case the gunk just buggers them up again, but I guess it'll just get discharged straight out of the PRV, won't it?

 

[stardanny]

You need to get a gassafe engineer to service and check as there is a safely recall from Baxi for potterton powermax HE range, there is a issue with a part of boiler that need to be check by an engineer.

Daniel.

 

[magicmanalex]

Thanks Daniel,

Yes, I read about this on mikertheboilerman's website (an excellent resource for us poor PowerMax owners!). It affects boilers manufactured between 2001 and 2005.

I called Potterton about a week ago regarding this safety recall and gave them the serial number of my 2007 boiler. They said it was unaffected and not at risk.

Thank you though.

I'm going to book a Potterton service tomorrow.