Worcester Heatslave 12/14 Oil Combi Problem

[xXCHAOSXx]

Just moved into our new house and for the first time ever have an oil fired central heating system. Had a few problems initially for the first couple of weeks. Got it serviced and seems better, but still not sure about one thing.
The hot water and heating seem to be operating as they should. I have a centaurstat wired in hallway and set times to suit our needs. But have noticed that if its set for an off period throughout the day it will fire up and put hot water through to the rads. It seems to be doing this regularly throughout the day for short periods, even if I select off on stat it will still do it. So needlessly using oil when I dont need it on.
Any one have an idea if this is normal, have always had gas combis before and never had this happen with them.

One other thing, because the hallway is fairly small with a rad in there, it soon warms up the hall and then switchs off the heating but other living areas are still a bit cooler. Thought of maybe looking at fitting a wireless room stat in the living room, so we can get living room up to desired temp as thats out main room.

Mark

 

[Burnerman]

This boiler fires itself up from time to time, just to keep the domestic hot water in its Heatslave tank nice and hot.
Within the boiler, just above the circulating pump, is a diverter valve that channels hot water to either the Heatslave tank or the radiator circuit.....therefore if the rads are getting hot when they shouldn't be, it's a reasonable assumption that this diverter valve isn't working the way it should.
John

 

[xXCHAOSXx]

Hi John, thanks for the info, thought it may have been a diverter valve issue but wasn't sure. Will have to get someone in to change it. Is there any way of preventing this cycling during the night or if away etc, when hot water is not needed, just trying to save as much as possible on oil consumption. Or is this only a feature on newer boilers.

 

[Burnerman]

If you have the digital programmer on the front panel, set it to shorter run times....this boiler heats up the internal tank pretty quickly anyway!
The complete diverter on this boiler is expensive......often enough it's just the power head on the top that needs replacing.
John

 

[oilhead]

Most often, if it is a Heatslave with a Honeywell V4044 valve, it's just a synchron motor that is needed. Does your valve have a silver/aluminium cover or a plastic cover? If silver, at the back of the valve is a manual lever. If this is sloppy, then the synchron motor is jammed. If you have a plastic actuator, then is the indicator on the side sloppy, if so, then the cartridge in the valve has probably seized and will require a drain down to replace the cartridge. That is where you hope the flow and return have isolating valves on them.

 

[xXCHAOSXx]

I'm positive it's a square shape silver cover, I've seen a lever on it but not touched it, will have a look and post back my findings. I assume it should be checked while switched off ?

 

[oilhead]

Whilst switched on, set the heating thermostat to full , and the DHW thermostat to zero. The laver should be sloppy. Move it over to the left looking from the top. Then switch off the heating, and turn up the hot water to full. Watch the lever, it should move back to the right. There will always be a little free movement on the lever.If it doesn't, Then your problem is with the actuator, probably the motor.
Switch off the power, remove the head, ( 2 screws) and you can then access the screw holding the motor and wiggle it out of the slot on the other side. The little drive cog should move freely when twisted by fingers rather like a friction drive toy car.

 

[xXCHAOSXx]

Sorry, been a while since I started this post, other problems to contend with. Anyhow, still having problems with boiler. Now, the last few months i have had to buy and fit a new expansion tank. Old one had perished and was full of water so everytime heating was on it was going over pressure and discharging through PRV. Then there was a constant clanging noise while heating was on and then hot water was run. Put this down to diverter sticking. Had a new valve and motor above it fitted. Boiler now quiet but im still getting heat to all rads several times throughout the day when its not called for.
I changed the original thermostat in my hallway from the centaustat to a honeywell wireless CMT901. Relay/reciever box in boiler room. But still same. Cant understand why it would do this. Must be something diverter valve related. I can have my stat set to off but still a few times a day the rads get hot.
Out of curiosity I removed the multiplug off the main control board for a day and hey presto, no heat when not required. Now im thinking maybe could it be a fault on main board causing this to happen or am i missing something. Had a oil boiler engineer do the diverter and he was also at a loss as to why this is happening. Could leave it and just get on with it but if its a warm day dont need rads coming on and its using oil when it shouldnt be. Anyone anyideas. ? Mark