Potterton Promax FSB 30 HE - Help

Checking the pump torque is down to experience but if it's low then that could be the cause.
When the heating and hot water demands are satisfied the zone valves will close...the pump can continue to circulate water via the bypass whilst it cools the heat exchanger (but only if the bypass is correctly set).
Have you tried removing the red pump valve handles and using a spanner on the spindle...
 
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Checking the pump torque is down to experience but if it's low then that could be the cause.
When the heating and hot water demands are satisfied the zone valves will close...the pump can continue to circulate water via the bypass whilst it cools the heat exchanger (but only if the bypass is correctly set).
Have you tried removing the red pump valve handles and using a spanner on the spindle...

The valves have (chewed) screwdriver slots, and one is seized tight. New valves & pump have just been fitted and system filling up now with inhibiter. I'll update after its working again...

Incidentally, the water is very clear when it was drained, plus the Magnaclean filter didn't have much debris in it at all.

I'll also get the by-pass setting reduced and see if it helps.
 
So an update:

New pump and isolation valves fitted, system refilled with inhibitor, and by-pass has been set at 0.2. System bled and everything fine.

However...

Right on the 20 minute mark, the boiler locks out in over-heat, which takes around 30 minutes to reset.

Guys have written down everything they've done on the boiler:


[*]Thermostat replaced on flow pipe
[*]Fan Thermostat replaced
[*]Thermister replaced
[*]Combustion chamber & outer door seals replaced
[*]Wiring checked - ok
[*]New pump - today

And I've adjusted the by-pass valve to 0.2, as well, before trying the system.

Only thing left is the PCB @ c £260

I'm scunnered to be honest, and reckon I'm left with the following choices:

1. Get rid of the cr@p and fit a new boiler, its actually 11 years old now, and I've no idea what boiler would be a good replacement (I'd prefer a really good system FS boiler)
2. Pay Baxi a fixed price of £335 for a one of repair, or £28 a month which gives me a repair and 12 months parts & labour.
https://www.baxi.co.uk/service-and-repair/book-a-repair
3. Take a hammer to it!!

Any advice, suggestions or other things to try or check would be great.

Thanks

Edit: The boiler has just went into overheat lockout on DHW only. First time its done that! :(
 
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If anyone has any ideas on this problem, I'd really appreciate it.

Thanks.
 
Does it modulate down as the flow temperature approaches the flow temp?
What sort of flow and return temps are they when it locks out?

It's a 25 year old dog of a design that's been problematic ever since it was launched.
 
Does it modulate down as the flow temperature approaches the flow temp?
What sort of flow and return temps are they when it locks out?

It's a 25 year old dog of a design that's been problematic ever since it was launched.

Thanks, yes it modulates down to a steady "burn", and seems to operate ok until it reaches the 20 minute mark, then locks out.

Both flow and return pipes (the ones I can get too) are both very hot, after its been running a while both feel about the same temperature.



I also called Baxi to pay for a fixed price call out, however after an hour or so on the phone setting it up, my post code isn't covered - I'm around 30 minutes for Glasgow city centre, so I find this incredible from a major boiler manufacturer!

So whoever reads this thread in the future, do not buy anything with Baxi or Potterton badge on it, and if you are tempted, make sure you check the after sales service fine print!!

If any kind soul on here has anything else I can try, that would be great.

Also, I'd really appreciate recommendations for a new FS system boiler for a 4 bedroom house - I may need to now bite the bullet and get a new boiler.
 
The Potterton name has finally been dropped from the Baxi lineup.
You should understand that all large holding companies such as Baxi have a line-up of boilers from several manufacturers in their group despite being badged as Baxi.
For instance Baxi also have a range that are made by Remeha in the Netherlands...they really are to be avoided due to the parts prices.
There are some straightforward reliable models from Baxi and some dogs....but it's only the trade that know that.
Do not buy by brand name alone...it's the model that counts.
 
your biggest problem is that when your boiler is at Min output it is still around 10KW, that is far too much to dump into 1 rad , as already said a poor design when it was new , there is a fix that can sort this but not something I could advise about on here, have done it a few times with success, but would never advise it as a DIY fix
 
Thanks for all comments. It looks like I'll need to replace.

I would appreciate any recommendations for a new FS system boiler. Or top 3 recommendations.

Thanks
 
There's little choice with floor standing boilers, you really can't go for wall mounted?

Whatever you do don't touch the Ideal Mexico HE...that's just the old Isar/Icos junk inside.

The Worcester Greenstar FS 30 CDi heat engine has been tried and tested...been around for nearly 20 years.
Some installers can obtain the 10 year warranty at no extra cost.
 
There's little choice with floor standing boilers, you really can't go for wall mounted?

Whatever you do don't touch the Ideal Mexico HE...that's just the old Isar/Icos junk inside.

The Worcester Greenstar FS 30 CDi heat engine has been tried and tested...been around for nearly 20 years.
Some installers can obtain the 10 year warranty at no extra cost.

Might be able to convert to wall mounted, but space in the utility room is very limited.
 
I thought out of politeness and gratitude to all contributers, that I'd close this out and to perhaps assist others who happen upon this issue.

For the past 4 days, the boiler hasn't locked out in overheat, and I've no idea why its stopped doing it. In addition to all the options tried, I discovered that the DHW stat was turned up too high (85 degrees), and I don't know whether this was a contributing factor or not. Its now set at 60 degrees, and family members warned not to touch it!

The bypass is also set at around 0.2, and new pump is set around medium speed. It may well have been a combination of things - who knows, and I guess time will tell. Fitting a new boiler is on hold for now, however, I now know which way to go if it packs up again. (sticking with a conventional boiler)

Anyway, thanks for all the advice, its much appreciated.
 

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