Baxi Solo 3 30PF not getting to full temperature.

[SteveRB]

This boiler is a heat only system. Started last year not getting the rads anyware near as warm as usual, although it has been fine for several years running at about 5 on the boiler control setting. Fixed a clip on thermometer onto flow pipe from boiler, and only read 60ish Deg. Should be around 80 deg. I believe. Suspected that the control pot (boiler setting) may be faulty, but exchanged that with no change. Replaced clip-on thermister on boiler outlet pipe, no change. Fitted new PCB, no change. I have just tried removing clip-on thermister from outlet pipe temporarily, and temperature did start to rise so I thought I might have a faulty replacement, until at about 65 deg. the overheat device triggered! Cant see them both being faulty, and tried several times with same result. The boiler works fine in all other respects, flame, heat up time, etc. Struggling now, anyone any ideas please? Searched but can't find anyone else with the same problem. Steve

 

[Agile]

How is your thermostat calibrated?

 

[SteveRB]

Thanks for the reply Agile. If you mean the boiler thermostat, it just has numbers from 1 to 6. Steve

 

[Agile]

OK, so if you set it on max then what are the flow and return temperatures?

What are you using to measure them?

 

[SteveRB]

It is set on max (6) when I only get 60-62ish on the flow and just 48-50 on the return. Using a good quality clip thermometer.

 

[Agile]

Is this an electronic digital thermometer?

 

[SteveRB]

No it's analogue.

 

[Agile]

Electronic?

 

[SteveRB]

No.

 

[Agile]

Well I don't consider those small bimetallic things very accurate or very easy to read either!

If it was accurate there is clearly something else wrong.

But the first think that I would be doing is to measure the temps accurately with a thermocouple digital instrument.

Tony

 

[Terrywookfit]

Have you gas rated it??

 

[steve32]

Have you checked pipework for blockages before you started changing parts.

 

[SteveRB]

It was gas rated when it was fitted, and nothing has changed, flame burning really well, nice and blue, looks like it always has been. Anyway that wouldn't explain why the temperature control system was turning the boiler off, would it?

 

[SteveRB]

Pipework not been checked for blockages, but 22m until 3" from gas tap under boiler then 15 mm. Wouldn't I notice a bad flame if gas was restricted?

 

[Terrywookfit]

That is why gas rate / wp is checked each service.
If you have a 12° temp diff but only a 60 flow, it is worth checking.