Baxi 105E

[Paul68]

Hi can anyone help!
I have a problem with the central heating on the above boiler since summer 09. Three radiators work correctly all the others are either cold or just warm, there are no fault lights showing.
Each radiator worked after purging individually, turned on one at a time and again only three radiators worked correctly.
Called in a boiler engineer who spent a day doing similar to what I had already done, on my return the problem was still the same and the engineer is not answering his phone.
I have tried cleaning fluid and ran for four weeks. I have also drained and flushed the system, refilled system but the problem is still the same.

 

[gaspro1981]

check the filter in the htg return isolation valve

 

[Paul68]

Hello Gaspro,

I tried that. Filter is clear. I found light brown debris. Flushed with loop until clear.
The return pipe is cool. The flow is mad hot.

Thanks.

 

[NatB]

Check the pump is working properly. I had this problem and a few others for a while which were solved when a new pump was put in to get the hot water moving round.

 

[Paul68]

How do I check if the pump is not working properly? or is it just a matter of replacing it and hope that was the problem

 

[Syncro]

Look at the box on the side of the pump where the electrical connections are, there's a white switch with a slot to turn it, make sure it's in position 3, which is the fastest flow rate and most power.

 

[wetshoes]

Might be worth cheching if there is a bypass fitted in the system somewhere, that's open too much.

 

[NatB]

Look at the box on the side of the pump where the electrical connections are, there's a white switch with a slot to turn it, make sure it's in position 3, which is the fastest flow rate and most power.

If you do find the selector please tell me the part number. The 105e doens't have one (apparently!) and it has an auto bypass.

The only way I could think to check pump performance was to close all rads except closest and just feel how hot it was before the boiler switched off.

Have you tried balancing the system, helped in my case until the pump went completely.

 

[Paul68]

Hello,

I flushed the system twice. I then took each radiator off ( 10 ) and flushed them. I then fitted a complete new pump. Re-pressurised but the problem is still occuring.
Red hot flow and cool return. Purged each rad and they all get hot individaully. I stripped the old pump. The fin was jammed. Freed it and the pump now works.
I undone the return where the filter is and flushed with the loop until clean water but could the problem be a partial blockage further away on the 22mm ?
Any ideas,
Thanks.

 

[NatB]

How does the return heat if you close all rads apart from the first two with their valves fully open?

You could try and isolate any possible blockages on the return by measuring the heat coming out of return side of each rad individually, whilst the others are closed, compared to what you're getting back at the boiler.

EDIT: by the way, I'm still having a similar problem with my boiler but only on lower temps. An RGI I had out was eyeing my magnaclean up and has suggested it's restricting flow as everything else checked out ok.