Potterton Promax 24SL – Heat Exchanger Leak – Repair or Replace?

[hy288]

Hi all,

We have a Potterton Promax 24SL system boiler, now around 13 years old. It’s been running reliably overall, with no noticeable issues until the past few months.

Occasionally, we’ve noticed a few drops of brown liquid leaking from the front of the casing — maybe 3 or 4 times over the last 6 months. The most recent instance was in March. Otherwise, the boiler is working fine and the pressure remains stable.
Due to the intermittent nature, i assume its a very slow leak under certain conditions and when cold stops?

We recently had an engineer out for a routine service and inspection. They spotted some leakage and staining around the flow and return connection points at the heat exchanger and manifold. Based on that, they suspect worn seals and recommended a boiler replacement rather than repair, citing potential issues with seized fittings and difficult access.

Has anyone experienced similar issues with the Potterton Promax 24SL and gone down the repair route successfully? I'm trying to figure out if replacing those seals is straightforward maintenance or if it's as awkward and time-consuming as suggested — to the point that replacement really is the more practical option.

Would appreciate any thoughts or shared experiences!

Thanks in advance.
Hung

 

[kidgreen61]

I think most pros on here will tell you to change the boiler, they're not v popular with engineers, you've been lucky to get 13yrs out of it.

There's an estate in my village which was built around 13yrs ago, all fitted with those boilers, I've changed 6 of them over the last year or two.

 

[hy288]

I think most pros on here will tell you to change the boiler, they're not v popular with engineers, you've been lucky to get 13yrs out of it.

There's an estate in my village which was built around 13yrs ago, all fitted with those boilers, I've changed 6 of them over the last year or two.

Thanks for your feedback. Yeah sounds like this Potterton was the standard issue across many new builds 10-13 years ago.

The engineer that initially came to service, suggested that i don't service and just replace. However, he did not get back to me with a quote for replacement. So made me wonder about his advice, and hence my post just to get other feedback.

I'm not against changing it, as anything over 10 years sound like a suitable candidate....so something i would be incline to do.
However, finances have been a bit tight this year so trying to prioritise and delay if possible (6-12months). Hence why i was wondering if my situation for a simple repair that might be cost effective to delay the replacement i.e. quick easy fix without massive amounts of labour (~£150-250).
or perhaps not a simple repair with alot of effort that might make a replacement a better option to take the hit now.

 

[kidgreen61]

Might be worth asking someone else to look at it, sometimes it's as simple as the condi trap leaking, they're prone to cracking.
The other favourite is the flow switch assy.
If the hex is leaking, then it's scrap.

 

[hy288]

Might be worth asking someone else to look at it, sometimes it's as simple as the condi trap leaking, they're prone to cracking.
The other favourite is the flow switch assy.
If the hex is leaking, then it's scrap.

I'm certain its not the condensation trap.
If the leak is around the connection points on the hex i.e unions....is that still consider scrap? I recall seeing the stains around the hex connection points, and slightly below the manifold area.
Like you say, probably just need a someone to have another look and quote for the replacement at the same time?