Hot Radiators - Yet CH is OFF!

[Gavski]

Here goes...apologies for long windedness...

Moved in to new house (3 bed semi) in the summer. I am a First Time Buyer so never had to worry about Boiler and CH heating probs before.
Found out that water was being run off the immersion heater tank in airing cupboard in the main bedroom.
Told the most effective way to heat water was to use the combi (also weirdly installed in main bedroom) (only recently too) (had a carbon monoxide alarm in room too)
Boiler is Halstead - Hero
So switched off the immersion heater.

Have a timer control panel in the airing cupboard for CH & HW. This is set to TWICE for HW, once in morning and once evening.
The radiators in the house all have temp controls on the side, these have been all set to OFF/*
Turned these on a couple of weeks ago while it was cold one night.
Fine - all worked (bar the bathroom one but that just needed bleeding - working fine now)
Turned CH back to OFF as didnt need it any longer.
Then have begun to notice that radiators I have left on at the side on temp control are coming on when the HW comes on!!
Have noticed that this is the only when the HW comes on - thru Half Term last week noted that radiators weren't on during day.
NB. the radiator in the hall is warm during most of day - but presume this is because it is directly below airing cupboard. gravity and all that.

I have tried to turn the CH on and off and see if it makes a difference, tried advance, but haven't really noticed a change.

What do I do? Is there something I am not doing correctly?
Some sort of switch I am missing?
Or is it a valve at fault sending the hot water to radiators too.

Im a bit nervous of this as its my first house and would hate for it to be a major problem!!!

Thanks in advance guys

Gav

 

[Strachan]

Combi you say?????? Sounds pretty much from your description that you`ve a system boiler with a 3 port valve that`s stuck in hw and ch mid position. Changing the synchro motor in the head is an easy enough task, get the model number from the valve and and get a motor to suite. cost about £12.

 

[Gavski]

Brilliant.

Can i ask if this is the right thing to get?

http://www.onlineplumbingsupplies.co.uk/acatalog/HoneywellMotor.pdf

I took a look at the bit in the airing cupboard and its honeywell V4073.

Is it easy to replace? inexperienced DIYer here.

Just to clarify - just this bit needs replacing and not the whole head replacement unit which i think looks like about £50.

Thanks again!!

Gav

 

[Strachan]

inside the head is a little round motor, 2 wires to it. 2 little screws secure it to the valve head. You should try replacing just the motor. Ask at a spares place for a synchro motor for that model of honeywell mid position valve. saves draining the system down.

 

[JohnD]

If you are taking the motorised head off, then, before buying the new one, you should be able to turn the valve manually - this will tell you if it is the motor not working, or the rubber ball or whatever inside the valve is worn out. That way you will know what part is needed. You should be able to tell, by touching the pipes with uour hands, which ones get hot because water is being pumped round them. Gravity flow does happen... but hot water goes up, not down. If the hall rad is warm it will be because the pump is sending hot water to it.

Also....
You do not mention a room stat on the wall. Is there one? There should be. The boiler and pump should not run unless the cylinder thermostat, or the wall stat, or both, tell it they want heat.

As you seem to have a hot water cylinder, I doubt you have a combi. What makes you say you have? It might just be a modern condensing boiler. What is the make and model?

 

[ffg]

I hope it's OK to resurrect this thread.

I have a similar problem with a Honeywell V4073.

The valve opens correctly to HW, and to CH, when heat is called for. The problem is, it doesn't return on the spring when heat demand stops. It stays on the CH position. After a short while, the motor becomes quite hot, suggesting that it's stalled.

If I switch the mains supply off completely, it returns on the spring.

The boiler was replaced a while back with a Bosch/Worcester Greenstar 24i. I'm not sure if the problem with the valve has been there since then, but I don't think so - I think it was working correctly until the summer lay-off.

The possibilities seem to be

1. The boiler/programmer/pump/valve was wired incorrectly

2. The valve is faulty, and stalls in the CH position and gets stuck there

I've checked the wiring carefully (not easy as I didn't wire the boiler/pump and can't see how it was done) but the programmer and the stats (room and HW) seem to be wired correctly.

Does anyone know if these valves can stall in this way? Don't want to replace it if it's not faulty...

many thanks

 

[gas4you]

I'd put a new head on it.

 

[ffg]

Thanks, Dave.

On further checking, it appears the 4073 is opening and closing correctly, in response to CH and HW demands, but for some reason if demand ceases when it's in the CH position, it just stays there, even though in doing so it's using power and the motor is getting quite hot. If the CH stays off and the HW demands, it goes to HW, then if demand ceases it stays there as long as the CH doesn't demand again.

Perhaps they all do this, or maybe it's getting conflicting signals from the (rather old) Potterton controller?

Slightly worrying that the valve is likely to be stuck on CH, getting hot, probably all night after the system switches off.

 

[gas4you]

These valves should rest in the DHW position. Could be the valve body is sticking.

In your case I would suggest replacing the complete valve to be sure.