Diverter Valve? Hot water but no CH

[pavementpizza]

Strange one this...got a 7 year old Ariston 27 MFFI with a Landis digital timer unit and ext. thermostat. Hadn't had hot water for a while and the system was making a lot of screeching noises and then the timer stopped working other than the over-ride boost button which is the only way we could get CH (but still no hot water). Called an engineer in (this was after the first one told us to simply get a new system because a new diverter valve alone was £200+...sussed he was an idiot fairly early on) and he fitted a new diaphram and we got hot water (hurray!). He checked the wiring and said the timer unit and the thermostat had been wired incorrectly and that there were at least another 7 wires going into the spur (in which the timer and thermostat were running through) that he couldn't explain and nor could I. He said the system simply needed a live feed and the timer unit on the Ariston itself was perfectly adequate. I agreed and he disconnected the timer and the thermostat.

Since then we've had hot water - the system kicks in after a couple of seconds when the hot water tap is turned on but despite setting the in-built timer and trying every setting possible (over-ride, continuous, timer activated, etc) the radiatots don't get any heat. When the system is activated the gas fires up but shuts down about 15 seconds later and the whole unit makes a lot of gurgling noises (not unlike when it is running OK).

Tried turning off the rads, bleeding, etc. but no luck and the engineer has disapeared off the face of the earth. Loath to get another in before I have some idea myself...any ideas?

 

[dal5band]

The diverter valve should have a manual lever so you can open the CH direction to get you going until you get the electrics going.
It may be the motor of the diverter valve is in fact the problem. You need to check if the diverter valve is getting power first.
I think a new motor is about £35 - you can change it without touching the plumbing side.

 

[pavementpizza]

There is a small trigger type switch on the opposite side of the bit that holds the diaphragm which moves when the hot tap is turned on and then springs back after. Is that the manual lever you mean? If it is is seems to be in the CH position already.

 

[dal5band]

Sorry mate, I think we are at cross purposes. Yours is a combi boiler dosn't have the traditional diverter valve.
You just need to check that the pump is running.

 

[pavementpizza]

No worries. I know which bit is the pump but how do I check it is running?

 

[croydoncorgi]

Stick a screwdriver against the pump casing and your ear against the end of the handle. If you can hear rumbling noises, the pumps running.

 

[pavementpizza]

No, it's not rumbling but it must have been OK before the new diaphragm was fitted because the heating was fine.

Any more ideas?

 

[fitz1]

check for 240 volts a pump.

 

[pavementpizza]

You'll have to explain how...!

 

[fitz1]

have u any knowledge of electrics?

 

[ChrisR]

Bleed the pump? Shouldn't be necessary but...
Undo the big central screw screw (dribbles) and and poke a screwdriver in while it's running.

 

[pavementpizza]

I have already undone the screw and it dribbled and then tighted it up again. This was with it turned off...it that right?

 

[dal5band]

Persumambly you listened for the pump with the CH on and it is not running. If so I would say your pump (i.e CH) was left disconnected by the last person. Get an electrician in.

From the internal clock, when CH is on, power needs to go to the thermostat and then to the boiler+pump. This is all at 240V so you don't want to be messing about.

 

[pavementpizza]

Appreciate the help...I agree (as a layman) that it appears the last engineer failed to reconnect something he disconnected. I'll try him again tomorrow and then get someone else in if he still doesn't answer..and then send him the bill.

Thanks again.

 

[pavementpizza]

Turns out he had disconnected a motorised valve which he didn't know existed. Took him two minutes to suss it...but took me an hour to take up newly fitted carpets and floorboards to find the valve to switch it to manual. Having said that it was worth adding that with only one thermostat the valve was redundant and didn't need to be there in the first place.

Hot water, hot rads and no screeching noises.

Only problem is I have no excuses for bathing the kids now...oh well.

Cheers