Hi,

I have a gravity fed hot water system powered by a Baxi Back Boiler
(Baxi Bermuda 552) which recently stopped working.

On removing the fire front I could see that the flames were burning
yellow and not the expected blue colour. It turned out that the burner
bar in the boiler had rusted pretty much to a powder! (The boiler is
about 20 years old).

I replaced the burner bar and the flames now look healthy and blue,
but the radiators are only getting tepid. The system is full of water
(I checked the header tank in the loft) and the radiators are all
bled. The boiler is burning constantly.

Could the pump also be broken? It seems to vibrate but does this mean
it's actually working?! How can I go about testing the pump?

Another question I have is why does there seem to be only one pipe
coming out of the boiler to feed to the radiators? It comes out of the
right hand side of the boiler and the splits into two with a T-piece.
The T-piece seems to have a direction of flow arrow on it. Is it some
kind of clever valve?

Any advice appreciated.

Markus

In an earlier contribution to this discussion,
Markus Splenius wrote:

Hi,

I have a gravity fed hot water system powered by a Baxi Back Boiler
(Baxi Bermuda 552) which recently stopped working.

On removing the fire front I could see that the flames were burning
yellow and not the expected blue colour. It turned out that the burner
bar in the boiler had rusted pretty much to a powder! (The boiler is
about 20 years old).

I replaced the burner bar and the flames now look healthy and blue,
but the radiators are only getting tepid. The system is full of water
(I checked the header tank in the loft) and the radiators are all
bled. The boiler is burning constantly.

Could the pump also be broken? It seems to vibrate but does this mean
it's actually working?! How can I go about testing the pump?

Another question I have is why does there seem to be only one pipe
coming out of the boiler to feed to the radiators? It comes out of the
right hand side of the boiler and the splits into two with a T-piece.
The T-piece seems to have a direction of flow arrow on it. Is it some
kind of clever valve?

Any advice appreciated.

Markus

How many pipes are there in toto connected to the boiler? - (there are 4
tappings, two each side)

Does the hot water still get hot ok?

Do the radiators get a bit warm in the summer when you have the boiler on
just for hot water? If so, you may have some gravity circulation in the
heating circuit - and this is perhaps what you have at the moment if the
pump has failed.

The pump should have an end cap which unscrews to reveal the end of the
shaft (very little water will come out when you remove the cap). You should
be able to see the shaft rotating. If it isn't rotating, it may have stuck
on a bit of crud and need freeing. Turn it off and rotate it a bit with a
screwdiver (there should be a slot for the pupose in the end of the shaft).
If it still doesn't rotate, check that it is being fed with 240v - and check
the wiring back through the room stat (assuming you've got one) to the
programmer. If it's getting 240v but still not rotating, it's time for a new
pump. [Providing it has serviceable isolating valves either side, it's not
too difficult to change - and doesn't require the system to be drained].
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

"Markus Splenius" wrote in message
...
Hi,

I have a gravity fed hot water system powered by a Baxi Back Boiler
(Baxi Bermuda 552) which recently stopped working.

On removing the fire front I could see that the flames were burning
yellow and not the expected blue colour. It turned out that the burner
bar in the boiler had rusted pretty much to a powder! (The boiler is
about 20 years old).

I replaced the burner bar and the flames now look healthy and blue,
There are a number of other implications in respect of ensuring the safe
working of the boiler such as flueing, ventilation, etc which i hope you
have taken care of but lets concentrate on your particular queries for now.

I was distinctly under the impression that the 552 was now obsolete so where
did you get the "burner bar"?
If it was out of an old boiler unit was it from the same model and rating
and has it got the same injector size and burner pressure as your old one?


but the radiators are only getting tepid. The system is full of water
(I checked the header tank in the loft) and the radiators are all
bled. The boiler is burning constantly.

If the boiler is burning constantly the heat input is not adequate to
satisfy the heating load on it.


Could the pump also be broken? It seems to vibrate but does this mean
it's actually working?! How can I go about testing the pump?

If the pump is not pumping then heat is not removed from the boiler hance
the boiler temperature rises and the burner is switched off by the
thermostat so i'd say no its not broken

Another question I have is why does there seem to be only one pipe
coming out of the boiler to feed to the radiators? It comes out of the
right hand side of the boiler and the splits into two with a T-piece.
The T-piece seems to have a direction of flow arrow on it. Is it some
kind of clever valve?

Its an injector tee. The pumped water circuit enters via one end of the tee
and the water flowing across the branch port induces a flow from the branch
pipe rather akin to the way a paint sprayer works by blowing air across the
suction pipe from the paint resevoir. For a fuller explanation look up the
works of Bernoulli and venturis.
The baxi is coupled to the primary of the hot water cylinder and heat
produces a thermosiphon (gravity circulation system). when the heating
circulation pump is running the injector tee encourages the sharing of the
boiler heat between the radiators and the hot water.

On Tue, 4 Jan 2005 22:35:14 +0000 (UTC), "John"
wrote:

I was distinctly under the impression that the 552 was now obsolete so where
did you get the "burner bar"?
If it was out of an old boiler unit was it from the same model and rating
and has it got the same injector size and burner pressure as your old one?

It's a genuine baxi spare part. The boilers are obsolete but spares
are still available. The only reference I could find to it on the net
was he
http://www.pricerightheating.com/Sho...pProduct2Id=86
but my local heating spares company had one in stock.

but the radiators are only getting tepid. The system is full of water
(I checked the header tank in the loft) and the radiators are all
bled. The boiler is burning constantly.

If the boiler is burning constantly the heat input is not adequate to
satisfy the heating load on it.

When I posted the message I wasn't being very observant - the boiler
stops burning every few minutes.


Its an injector tee. The pumped water circuit enters via one end of the tee
and the water flowing across the branch port induces a flow from the branch
pipe rather akin to the way a paint sprayer works by blowing air across the
suction pipe from the paint resevoir. For a fuller explanation look up the
works of Bernoulli and venturis.
The baxi is coupled to the primary of the hot water cylinder and heat
produces a thermosiphon (gravity circulation system). when the heating
circulation pump is running the injector tee encourages the sharing of the
boiler heat between the radiators and the hot water.


Could the injector T be broken or partially blocked in some way?

Is it possible that the heat exchangers at the top of the boiler are
not working fully for some reason?

Thanks

Markus

"Markus Splenius" wrote
| When I posted the message I wasn't being very observant - the
| boiler stops burning every few minutes.

Pump knackered or system badly sludged.

Owain