2 seperate heating systems - how do they work together?

[steph]

I have recently moved house and trying to understand how my heating systems work, and this is because it seems to be inconsistent. Firstly to explain my setup, I have a normal heating system with a tank in the loft and cylinder in the airing cupboard and Honeywell wall stat. My house also has an extension with underfloor heating in. This has a digital thermostat on the wall.

What I don't understand is why my heating system is inconsistent. When i use the digital thermostat in the extension, sometimes all the radiators come on in the house and at other times it's just the underfloor heating that comes on in the extension. And when I use the original wall stat in the house, sometimes all the radiators come on in the house (albeit minus the extension), and at other times they don't and I only get hot water. Why? Are the two systems in conflict with each other? I have a separate 3 port valve for each system - could it be their positioning? I notice the lever on the 3 port valve for the original house has no resistance when i push it so I think the motor or whole head unit needs replacing. I touched the motor and it was very hot - i thought it was only meant to get warm?

Thanks for any thoughts!

 

[Johnyc86]

I have recently moved house and trying to understand how my heating systems work, and this is because it seems to be inconsistent. Firstly to explain my setup, I have a normal heating system with a tank in the loft and cylinder in the airing cupboard and Honeywell wall stat. My house also has an extension with underfloor heating in. This has a digital thermostat on the wall.

What I don't understand is why my heating system is inconsistent. When i use the digital thermostat in the extension, sometimes all the radiators come on in the house and at other times it's just the underfloor heating that comes on in the extension. And when I use the original wall stat in the house, sometimes all the radiators come on in the house (albeit minus the extension), and at other times they don't and I only get hot water. Why? Are the two systems in conflict with each other? I have a separate 3 port valve for each system - could it be their positioning? I notice the lever on the 3 port valve for the original house has no resistance when i push it so I think the motor or whole head unit needs replacing. I touched the motor and it was very hot - i thought it was only meant to get warm?

Thanks for any thoughts!

Think you need to change to an s plan heating system

 

[SimonG]

Pictures would be a good start

Definitely sounds like a control issue.

 

[SJB060685]

What programmers do you have?
I'm struggling to picture your setup without seeing it personally.

 

[king of pipes]

As the guys have stated pictures of the system are needed here , a system like this would normally be piped as a Honeywell S plan plus system using three 2 port valves one for each circuit and have timed and temperature control for each ?? Kop

 

[Murdoch]

Definitely sounds like a wiring / control issue and the bit about the hot water sounds odd too

 

[steph]

Thanks for your replies...photos attached. And just noticed it is a 2 port valve for the underfloor system with a pump, and an additional pump in airing cupboard with 3 port valve.

 

[SimonG]

Holey Moley that looks a quality install on the underfloor.

Best bet is to get somebody on site who is familiar with heating systems and their wiring. Set of testers and some time will get you sorted.

 

[king of pipes]

With a three port valve your either have heating only , hot water only or both , add in a underfloor circuit then the three port heating circuit needs to be open so the primary heating hot water can circulate around the system and back to the boiler to be heated , the issue you having is possibly caused by the heating water short circuiting and creeping up the return into the radiators ect when it should be off or satisfied, needs a engineer who.know his way round a multimeter and probably a modification from a three port to two 2 ports plus your underfloor valve . Kop

 

[SJB060685]

A two port and a three port (be it diverter or mid position) makes sense now. There's no reason why this layout can't work, providing installed and wired in correctly. As above try to find someone familiar with UFH and competent with heating system wiring.