Baxi Combi 80e Help Needed!

[daKlone]

I wonder if someone could please help me diagnose the problems with my Baxi 80e Combi boiler?

It doesn't seem to working correctly and it's pretty annoying!

The problems are these:

1. DHW gets hot, then goes stone cold, then gets hot again...makes for an "exciting" shower experience!!

The boiler ignites when the DHW is on, temperature climbs to max (80 degrees) and then switches off. When the 80 degree lamp goes out, it re-ignites. Makes no difference what I set the temperature control to, this is the pattern.


2. CH doesn't seem to heat up thoroughly.

When I call for CH, the boiler ignites and brings the temperature to that set on the temperature control but then goes off. Temperature drops to nothing but it doesn't re-ignite.


There are never any fault indications on the front panel lamps for either DHW or CH problems.

Last year I had the diverter valve and DHW flow valve diaphragm replaced.

Any suggestions on what might be wrong, or additional observations I need to make to help figure it out?

Thanks in advance,
dK

 

[namsag]

Fault one is a dirty plate heat exchanger and needs cleaning or replacing cost 45 quid.
Fault 2 may not be the boiler it may be your room stat. try turning that up and down first when it plays up

 

[daKlone]

Thank you for your quick and succinct reply namsag!

The plate heat exchanger looks like a right nause to get out - is it a DIY proposition or do I need to get someone in do you think?

The CH is not behaving exactly as I first described in fact, sorry

It actually ignites, heats up to 80 degrees, goes off, cools down rapidly and then re-ignites about 4 minutes later to repeat the process. Controller is calling for heat the whole time.

 

[Agile]

The CH problem could be a poor flow rate or more likely a ssmall heating load and a boiler not adjusted tomatch it. That needs an RGI.

Tony

 

[daKlone]

Thanks Tony.

The CH has previously worked fine, does this suggest that it is the former rather than the latter problem?

 

[Youllneverguess]

Sounds like the whole system is choked for of sludge to me. Get it cleaned out and then worry about replacing parts.

 

[45yearsagasman]

Just a thought about choked systems and the like, is there not a filter in the return isolating valve on these?

 

[Agile]

I think there probably is !

It should be part of the isolating valve under the boiler.

Should have been fitted to return on the right but many were fitted to the flow on the left instead!

Turn off both valves and use a spanner to undo the front nut like part to expose the gauze filter.

Tony