Boiler runs all the time.

[dave21478]

Hello, A google search for info turned up this forum, hopefully you can help my situation.

My sister recently moved house and its fitted with an elderly central heating system. There is a gas fire in the living-room and the boiler appears to be behind this in the base of the old chimney.
A hot-water tank is located in the upstairs cupboard and in the attic is a small tank with float-valve for filling the CH system.
There is a timer control which allows seperate programming of central heating and hot water times.
In a cupboard next to the fireplace is a jumble of pipes fitted with a pump and 2 motorised valves (I assume thats what they are - grey boxes fitted in-line on 2 of the pipes)
Im assuming this is a gravity system yes?

Anyway, all was well until a few weeks ago when the boiler refused to switch off. It keeps igniting to heat water even though the programmer is set to off. The only way to stop this was to switch off the master switch, killing all power.

I assumed a faulty programmer and the guy in an orange apron at the local diy place agreed this was most likely. It was an elderly thing anyway. I replaced it with a new version with all the same features. It was a direct upgrade and didnt require changing the base-plate wiring.

All was well for a couple of days with the system performing as expected in a quick test.
Over the next few days, hot weather meant the CH was left switched off and the boiler was only used for HW. A chilly snap meant we switched on the CH for the evening and since then, the boiler is again refusing to stop heating. If left, this produces loud gurglings from the boiler and I assume we are wasting gas needlessly heating water.

I assume the programmer hasnt broken after a few days and probably the old one wasnt faulty after-all, and the fault lies elsewhere but havent a clue where to start?

Thanks for any help,
dave.

 

[HarrogateGas]

It is NOT a gravity system but sounds like an S-plan. I suspect one of the moterised valve end switches is sticking. you need to work out which val by pulling out the orange wires from each. If you pull one out and the boiler goes off, you have found your faully valve.

 

[dave21478]

Ok, thanks for the help.

In the cupboard, the 2 grey valves are "ACL Lifestyle 2 Port motorised Valves"

The wiring from each goes into a series of connectors on a box on the wall. Disconnecting the orange wires one at a time switches the boiler off when I disconnect the CH valve`s wire.

I assume this is the faulty part?

Changing this, do I have to remove the whole valve from the pipe-work or does the box of tricks come off and is it replaceable on its own? If so, how does it all come apart?

Thanks for your help,
Dave.

 

[ollski]

with the acl lifestyle valves almost all of them except very recent ones need the complete valve replaceing as the head doesn't come off. Try it though if it has a black push button opposite the w / m / h indicator just push it in and pull off the head.

 

[bab]

When the boiler stays firing are the rads getting hot. It may be the syncron motor thats stuck. If its 2 two ports do they have W/M/H on them Ollski? Is the plastic lever at the end loose or is there resistance when u try to slide it across.

 

[dave21478]

Ok, I stripped the old valve head down and discovered the wee microswitch was sticking in when the valve closed.
A quick soak in electrical contact cleaner cleaned it up nicely and it all works perfectly now.

Thanks to all.
Dave.