multifuel boiler and electrical issue

[stevejd58]

I have a Charnwood LA50 inset multifuel burner that has been installed for a year or two now.

The problem we have is concerning the pump and a pipe thermostat which i believe is to ensure the water doesn't over heat and to force the pump to run to dissipate excess heat via the radiators.

this is the set up that was installed.
it has a wireless room thermostat (Honeywell HCW80) in the hall
a honeywell ST9400 control unit
a Grunndfos Alpha 2 pump
a pipe thermostat of unknown brand (x2?)

we tend to run the pump continuously when the boiler is lit as I can't see the point of timing the pump on this type of set up, whatever the setting the fire will still be burning

what we have noticed is, more so when running on wood, is that when the water gets hot, he circulation pump cuts out (pipe thermostat?) and will only run again if some one runs a significant amount of hot water off.

I'm guessing during the installation the pipe thermostat was mis wired.
If you look at the pic, there are two wires that go behind the boiler unit, would there be a thermostat on both of the ascending pipes?
if so would swapping the thermostats over solve my problem or am I looking at a heating electrician

 

[Gboyder]

Sounds like stat is wired wrong, has it always been like this from installed? Stats can be wired NC (normally closed) or NO (normally open) yours sounds like it's NC, so it's sends power when cold and isolated when hot. It should be the opposite.

My opinion is I wouldn't want any water been pumped round my stove till it's up to temperature. Cold flue gases are very bad for flues. Dens and full of moisture, get the stove hot as fast as possible (about 250c) them get the pump going. Or the stat should do this for you that's what it's there for after all. Getting a stove up to temp fast with 100 litre of cold water been pumped round it may be very hard.

This is just my opinion tho, not a professional in this sector. Get someone that knows what there doing ! ����

 

[SimonG]

The fire is lit. The heat rises under gravity to the cylinder. Cylinder heats until stat satisfied. Normally closed valve is unpowered to close and protect cylinder whilst leaving gravity circulation to heat leak. Pump operates to run heating.

Could end up with cold water corrision in fire.

 

[stevejd58]

yes it has, I thought this was the problem.
Without removing access covers I think I have x2 pipe stats by the look of the cables going behind the stove,

 

[stevejd58]

The fire is lit. The heat rises under gravity to the cylinder. Cylinder heats until stat satisfied. Normally closed valve is unpowered to close and protect cylinder whilst leaving gravity circulation to heat leak. Pump operates to run heating.

Could end up with cold water corrision in fire.

I'm guessing this happens but the pump shuts down