Bermuda Baxi 552 fault

[Fiddler9]

Hello,
I have read about others with a Bermuda Baxi 552 back boiler but none are the same as mine and I wondered if anyone could help.

I have 3 upstairs rad's that get hot even when HW the only option selected.
I have now found that I have little or no hot water regularly. tonight I had HW on for 1.5 hours and only got the 3 RAD's hot. When I turn one off completely the boiler stops heating (presumably it thinks the water is up to temp).
I have varied the stat, by the pilot light from 3-4 to HIGH with no difference.

I don't appear to know where to find a valve that would separate the HW from the CH.
I can find the pump and that is purring away nicely.
I don get 3/4 of a tank of HW if I have the CH on for 4-5 hours.

Please help, especially on how to find the valve.

thank you.

 

[twgas]

first check the header tank in loft (small one) has water in, if not wiggle ball valve up and down to free it up so that it works properly. check on it after an hoiur or so to make sure it shut off properly when full

 

[gas4you]

When you bleed an upstairs rad do you get plenty of water out?

Where is your pump?

In your airing cupboard you may find a motorised valve or 2, but you may have a gravity HW system and the pump only does the rads.

This could be the case if your pump is next the the boiler in a false panel cupboard against the chimney breast.

We need more info as yet to help properly.

 

[Fiddler9]

Mick/Dave,
Thanks for the quick replies.
I just checked the small tank and there was an inch or 2 of water in it, wiggled and pushed the back down and I have filled it half way up, and it cut out when I let go. BTW, what is this tank for

As for the pump, it is in the cupboard under the stairs, and yes, it is a gravity fed HW system.
When bleeding I do get water out of the RAD's and only ever get air in the 3 upper rads that get hot when heating the water only.

Cheers
Chris

 

[gas4you]

As you have a gravity HW system, then the upstairs rads getting warm when the heating is on is normal unless you have an anti gravity valve fitted to the heating circuit.

If you are getting no HW then I can only suspect a massive air lock on the DHW side or a blockage.

You could connect a hose to a drain off cock and drain some water out and check that the small tank is emptying and re-filling as you are draining.

The small tank feeds the heating system and takes up the expansion of the water when it gets hot.

 

[Fiddler9]

Thanks Dave,
I'm guessing that the expansion tank having so little in it when the system is hot probably means when it goes cold it probably sucked in a lung full of air.

There is a drain off tap/valve next to the pump, If I empty and the expansion tank refill's will that be enough to clear the air out, or is there a bleeder valve somewhere for the HW ?

thanks again,
Chris

 

[gas4you]

Yes it could be that the system was sucking in air due to the low water level.

The draining suggestion was to check that there is no blockage in the cold fill from the small tank, not to get air out.

This should happen naturally once the tank is full again.

 

[Fiddler9]

Thanks for all your help,

I will drain tomorrow and post if I get no refill.
I will also introduce some WD40 to the expansion tank ball valve arm.

Can't get the ladders out now, kids are in bed.

Cheers

 

[Fiddler9]

Hello again,
Just to say thanks once again.

I have had plenty of hot water every day since I took your advice.
It was indeed the expansion tank having no water.

Cheers
Chris