CH queries

[ceolmar]

I have a baxi bermuda 552 gas fired back boiler. The system uses a Grunfos pump and a really knackered looking manual timer/controller with two toggle switches which offer timed, on/off - and water or heating priorities.

I recently turned the central heating on for the first time after summer. I noticed the pump frequently making a rattling noise which stops if finger pressure is applied to it from the left or right. The radiators get hot with no problem other than one rad neeeds to be bled. However, my main concern is no matter how I set the timer/controller toggles or the thermostat in the hall, the heating stays on. I have now turned the boiler contol right down just to prevent the system getting too hot. And, I don't seem to have a feeder/expansion tank in the loft!

Also, my copper cylinder has a thermostat near the bottom with an electric cable coming from it but it doesn't seem to make any difference how i set it, the tank still gets very hot even with the immersion heater turned off.

For information, over the summer I fitted a new mixer tap in the kitchen but thats the only change made.

Any ideas?

 

[ChrisR]

Could be the heating motorised valve stuck open ,(try whacking it with a screwdriver handle) or your old programmer has had it.

 

[ceolmar]

I have found my feed/expansion tank buried under some old carpet in the loft!

It has some water in it and I operated the ball valve to add a bit more. The little lever on my honeywell 3 port valve seems to have no effect whatsoever and just flaps about loosely. Is it past it? Is it difficult to replace? Will banging it with a screwdriver handle really help?

 

[ChrisR]

Turn mains elec to heating system OFF. If small lever still flappy, it's stuck open. It should start from a position where you push against a spring to open the valve and it whirrs back when you let go.

Whacking can work, as can undoing the 2 small screws which hold the head to the base of the valve, about half a turn. Don't unscrew if the top of the valve case does not have a pimple on it , or you get wet.

 

[ceolmar]

Thanks Chris I'm starting to get my brain round this(I think). I took the cover off the valve body to get a closer look at what the lever is doing. I saw the two springs which you refer to which presumaby both keep the lever arm under tension and return it to the auto position? However, the lever arm does not appear to be attached to anything hence it's flapping around

The 'leg' of the three port valve goes to the CH pump. One arm goes to a 22mm pipe presumably to the heat exchanger in the copper cylinder in the airing cupboard. The other arm goes into a 15mm pipe and disappears upstairs.

A new valve will cost me about £45 and replacing it will give me the opportunity to flush and treat the rest of the CH system. Many thanks for your time and feel free to offer more advice. Cheers