Boiler Reset

[chatrail]

Hi,

I have a heating system using a Baxi 552 back boiler. Last weekend I shut the system down. Drained the Rads and replaced a rad plus it's valves (rusted). I flushed and refilled the system and bled the rads (lower floor first).

So far so good - now the problem.

I think the boiler overheat stat has tripped beacuse the boiler fired up for a short while then shut down (pump still runing ok). I am thinking there must of been a bit of trapped air that tripped the stat.

I have now run the system for about 15 mins to ensure there is no trapped air, but I need to know how to reset the boilder overheat stat cos I'm getting cold

 

[chrishutt]

Does the boiler have an overheat stat? How do you know this? Is the pilot light still on?

I would have thought a blockage was the most likely explanation, either an air lock or sludge. Flushing and venting a system isn't always so simple.

 

[chatrail]

The pilot is still on and when I switch the CH on the pump runs, and you can just hear the movement of water, but the main burner in the boiler just will not fire.

It was OK before I drained the system to do the rad swap. I could try draining it again, but I can't see how the airlock would prevent the boiler from firing unless there was some kind of stat/flow sensor to stop it.

I have lost the manual for the boiler so I'm working a little blind.

 

[chrishutt]

Does the boiler have an overheat stat? How do you know this?

You did not answer these questions. I can't help you if you don't answer my questions.

 

[chatrail]

Sorry missed that bit.

I (rightly or wrongly) made the assumtion it has an overheat stat but without the manual it is an assumtion. It is based on the fact that after the re-fill the system did fire-up for about 30-60 seconds before the main burners shut down.

Again without the book of words, I'm not able to locate any stat or reset button. Being a back boiler it's not easy to see very much and I do not want to go down the road of removing the feature fire, thats a job for the CORGI boys and not me (the home owner)

I was hoping that someone out there was going to say - "yep the stat has tripped and the reset button is ...."

If you have any more thoughts please hit me with them, I'm happy to try your suggetion of drain and re-fill. Oddly enough I did have to drain the system about 2 years ago to move a rad, the system just "worked" after that refill

 

[chrishutt]

I'm happy to try your suggetion of drain and re-fill.

Did I suggest that? We seem to be having some communication problems.....

You can access a manual here, but if you keep making assumptions you won't get anywhere. Just note the actual evidence of what does or does not happen (and what people actually say, for that matter).

What we need to know is if the boiler flow water is hot. Can you get access to the flow pipe near the boiler to see if it's hot?

 

[namsag]

baxi 552 never had an over heat stat. As chris says airlock , cause system is running doesn`t mean all air is out or pump is pushing it around the circuit

 

[chatrail]

Chris, thanks for the link to the manuals, thats great!

You are right, I will stop jumping to assumptions.

OK - to recap, facts only.

I needed to replace a rad and it's valves due to rust, so I switched off the electrical supply to the system, drained the rads and carried out the swap out.

After the refill I ran the system on CH with the room stat way up to make sure the heating would come on. The pump was running OK but the flow pipe from the boiler was cold. The other half was sure she DID hear the boiler "fire up", but by the time I came back down from the airing cupboard and looked into the pilot light window the boiler was sitting there with just the pilot on.

I switched off the CH, thought for a bit, checked the rads for air, and then gave it another go. I couldn't hear the boiler kicking in to life but after about 3 mins the flow pipe DID show SLIGHT signs of being warmer then the return, and the pump was running fine, but the flow pipe never got any hotter (after about 5-10 mins).

It was at this point I became stumped, looked to the Internet and started making assumptions about overheat stats.

Paul.

 

[chrishutt]

OK, now we're making progress. Presumably your system also heats the hot water in a cylinder. Do you know if the circulation from the boiler to cylinder is pumped or gravity?

On the flow pipe from the boiler to rads, is there any high point that does not vent air naturally into a radiator or the boiler itself? I'm assuming that the boiler itself is vented via the flow pipe to the hot water cylinder.

When you drained the system, was the water very black with sludge?

Are you sure the feed tank has filled to its normal level?

If you could let me have answers to those questions we might get somewhere.

 

[kevplumb]

want to calm down bonny lad
starting to sound like glazier
or should that be god
the lad is struggling
you know the job i know the job
slagging people off cos they don't BIG HELP
you might like to have a look at the name of this site

 

[chrishutt]

you might like to have a look at the name of this site

diynot.com - well, I've sometimes wondered just what that means....

But I take your point kev, I do have a tendency to sound pompous, but who's perfect? I don't mean to slag anyone off, just trying to get them to recognise that they're making assumptions or asking the wrong questions.

I like to think that I try to help people find the solutions to problems themselves, rather than do it for them.

 

[kevplumb]

fair comment chris
thats why i have been here for the thick end of two years
sometimes it's like pulling teeth

 

[chatrail]

Chris - The system does also heat water. There is a diverter valve to switch the boiler from the rads to the cylinder, and the pump is just before that valve so it would be pumping for both.

I think there is a high point, but I'm at work right now so can't check, I will take another look tonight so I can be accurate about that point, same for the boiler venting. There is a an "upstand" pipe on the upper of the two indirect connections to the cylinder, this terminates in a a device that looks like a large end cap, its a little hard to get to, so sorry for sounding vague. From memory that looks to be the higest point.

When the system was drained is was very black and the rad I replaced was full of blank sludge.

I did check the F + E tank and it is at it's normal level.

Thanks,

Paul.

 

[chrishutt]

There is a an "upstand" pipe on the upper of the two indirect connections to the cylinder, this terminates in a a device that looks like a large end cap

This is an air vent point. It will have a knurled knob or rad style vent or screwdriver slot. Open this a little, air will hiss out and then water. Close it and sit back and be amazed when everything works properly. Post a message here to say how wonderful the forum is, etc.....

At least the hot water side will work. You may still have probs with some rads on CH side due to sludge or air locking.

 

[chatrail]

Chris, spot on!

One rad key, one hiss of air, one spurt of water, one warm and happy man.

I'm now sat back in amazement and gratitude with a glass of wine, toasting it to you and diynot.

Sorry about my first posts cos I now see I was totally on the wrong track, and many thanks for your help and sticking with it.

Cheers,

Paul.