Baxi Solo Overheat tripping

[DarloCol]

Anyone with knowledge of older Baxi boilers?

Last week, had a MagnaClean fitted to my 10 year-old Baxi Solo 2 60 SR which serves a Y-plan heating system (pumped to rads, but gravity DHW).

Since then, the Overheat Cut-off keeps tripping. When fitting the Magna Clean, it seems the engineer removed something called an 'adapter tee with injector washer' that the Baxi Solo manual says should be used in combined pump/gravity systems such as mine. The manual states: "Failure to fit the injector washer will result in reverse circulation in the DHW circuit".

The engineer says this is not the cause of the problem, and probably the heat exchanger is all furred up.

He says the injector washer merely inhibits circulation and the only effect of removing it will be warm radiators when just using the DHW. I'm not convinced. The manual refers to reverse circulation IN the DHW circuit, not from it.

Any thoughts please, before I contemplate some kind of chemical clean to see if that resolves the overheating?

Cheers

 

[Billy Bob Bob]

yes i am not convinced either for a start why would you want warm rads when in dhw mode? one thing to consider the solo is a low water content boiler so relies on a good pump any weakness in the pump and the boiler will lockout

 

[wnjswozo]

get him to remove the magna thingy,re-instate the adaptor tee,you,ll see if it locks out.

 

[ferret]

you don,t have combined pump/gravity system if you have a y plan system .... as gas man says it is a low content heat exchanger and must have good flow through it , i suspect that the magna clean he has fitted has impeded the flow rate somehow although it should not at all , check it has been fitted to the return pipework and that the valves are fully open , also check that the pump is up to speed 3 and the boiler stat is not at max

 

[DarloCol]

Interesting replies so far.

In my silly lay-man kind of way, I was thinking perhaps the removal of the restrictor washer from the pumped return is allowing pumped flow back up the gravity return. This backflow is inhibiting circulation and water held back at the flow end is causing the overheating (and might explain why the hot water tapped supply is noticeably hotter too).

Is this feasible or am I talking horlicks?

 

[ferret]

you said you have a 'y' plan! , or do you have gravity hot water and pumped heating?? if you do then the overheat stat should have been bypassed at installation , therefore you cannot get lockout. if you do have gravity hw then the tee and restrictor are needed !

 

[DarloCol]

Thanks. Oops... I've got that Y-plan comment wrong it seems.

There are definitely separate pumped and gravity circuits.
This adapter tee was fitted at the boiler return tail with the injector washer seemingly reducing the flow from the pumped return as it merges with the gravity return.

I've seen the reference to bypassing the overheat stat in some manuals for more recent Baxi boilers, but I can't find it in mine. (Its been ok, though with the stat enabled up until now).

Bottom line is that the engineer suggests the boiler has got furred up, which could be right but my suspicions are that the issue is more likely to be due to the removal of the tee.

 

[Dave]

Hi darlo Col.. are you qualified to question the engineer..?.. Darlo hey.. just up the road from me..

 

[DarloCol]

Don't get me wrong, he's a good guy and no doubt I will follow his advice and will employ him in the future. But when things are complicated, it does no harm to get a second opinion.

Thanks all, ferret and Gas Man in particular.

 

[DarloCol]

Ferret, you are right - found it in my manual now that overheat stat should be disabled. It's been enabled for years!

 

[tamz]

The restrictor ring is needed "inject" the water past the gravity return connection into the boiler thereby preventing it going back up the gravity return.
It works by speeding the water up as it goes through the ring a bit like putting your finger over a tap or squeezing the end of a hose.

As Ferret said the OH stat should be bypassed by removing the wire and pushing it onto the double spade on the other side. This should have been done when it was first fitted.

 

[shelley.sidney]

Generally a boiler overheats when it is starved for water, there is no mention of service to the water supply. Is it automatic feed, is there a low water.

 

[ferret]

could you post a piccy of the installation of the magnaclean ? its possible from what you are saying about the injector tee missing that it is interfering with the return back to the boiler.

 

[DarloCol]

Here is a general view showing the Magna Clean and also a close-up of the returns. The gravity return is at the rear. Tamz and others point out that the removal of the injector washer means the pumped flow is no longer being pushed down into the boiler, passing the gravity inlet on way. It seems to me that the fitting of a horizontal tee is further encouraging reverse flow up the gravity return and reducing the flow efficiency of the whole system.

I am thinking it might be best to abandon the Magna Clean, refit a injector tee adapter (and, of course, isolate the OH stat as required in the installation instructions).

shelley.sidney: the system is tank fed and I am not aware of any water supply restriction.

Cheers All.

 

[Billy Bob Bob]

Here is a general view showing the Magna Clean and also a close-up of the returns. The gravity return is at the rear. Tamz and others point out that the removal of the injector washer means the pumped flow is no longer being pushed down into the boiler, passing the gravity inlet on way. It seems to me that the fitting of a horizontal tee is further encouraging reverse flow up the gravity return and reducing the flow efficiency of the whole system.

I am thinking it might be best to abandon the Magna Clean, refit a injector tee adapter (and, of course, isolate the OH stat as required in the installation instructions).

shelley.sidney: the system is tank fed and I am not aware of any water supply restriction.

Cheers All.

god what a mess

 

[tamz]

Your hw won't work the way it has been altered. He has created a high point on the return which will stop it circulating.

Put the tee back the way it was with the restrictor fitted. If you have lost it you can make something up with a 22 x 15 reducer, and fit the magnaclean on to the heating return somewhere. If there is no room above the boiler put it somewhere else where it is less of an eyesore.

 

[gasmarc]

i dont want to look at those pics yet i would NOT disable the overheat stat until I was 100% certain, why would it work for 10 years with no lockouts ?

 

[ferret]

i agree with tamz completely , but i,d get matey back to put it right , and do the OH bypass as the MI,s state .
good luck mate

 

[DarloCol]

My thanks to all contributors on this, but I am sure the rest of you won't object to me saying particular thanks to tamz and ferret for their detailed and useful posts and for taking the time and trouble to stick with it.

Ferret: great idea to upload photos (never occurred to me!)

Tamz: impressive IT and photo editing skills, by the way!

I'll post the outcome, but it will be 2 or 3 weeks as I am out and about and the guy I used is busy too.

 

[tamz]

Tamz: impressive IT and photo editing skills, by the way!

The grandwean taught me that one

 

[dogmangsd]

I have a baxi solo 3 pfl 60 boiler that over heats all the time needing to be reset, it is serviced by british gas who in the 5 or 6 years we have had it have been out so many times they put my service contract up to silly money and want to replace it with a nice one for 3500 !! I am so sick of them and this bloody thing in the kitchen , NO not her the boiler !
I am in Blyth Northumberland can anyone who knows what they are doing get in touch. why the hell it over heats I dont know, Bgas come fiddle run away and it isnt fixed. last time he wanted to power flush the system and charge 600 - 700 for that !

 

[Billy Bob Bob]

is your pump faulty? the solo relies on a good pump being a low water content boiler,you could have a corroded system and thats the systems fault not the boiler independents will clean it just as well(or better than)bg for much less

 

[dogmangsd]

Thanks for the reply that was quick, I dont know the pump seems ok , well it buzzes and the like when its working, how would I know if it was the fault

 

[Billy Bob Bob]

short of replacing difficult,but if its aged and lost its oompph ,this would have a bearing on your problem

 

[dogmangsd]

They recon of i pay them 3500 it will solve all the problems. So would spending 10k on a new car solve the problems I have with that! this time the boiler just isnt on no lights nothing going on. yes it has been overheating and cutting out after they were last out. but now its just off

 

[Billy Bob Bob]

tried resetting it? the solo is a extremely reliable boiler,not to be confused with the solo he which is tat