Heating and hot water digital programmer

[stem]

Could be, but the valve and p/w look like 28mm to me, which is a bit OTT for the CH circuit.

Good point. OP would you be able to tell us where A and B go?

I'm wondering if 'B' goes to the HW cylinder, and 'A' to the heating or vice versa. It could be 28mm from a converted gravity system maybe. A lot of guess work here, but without a definitive wiring diagram or pipe layout it's all we can do.

 

[fixitflav]

I'm wondering if 'B' goes to the HW cylinder, and 'A' to the heating or vice versa. It could be 28mm from a converted gravity system maybe. A lot of guess work here, but without a definitive wiring diagram or pipe layout it's all we can do.

Agreed, at the moment we're waiting for the OP. Then we might be able to see if it's a piping or a wiring problem. At the moment, my money's on the wiring.

 

[stem]

At the moment, my money's on the wiring.

Mine too, and sometimes, the wiring is wrong because it's a failed attempt to overcome a plumbing issue.

 

[Mister Banks]

Maybe on older systems, with gravity HW, not on a fully-pumped system. But we'll see, hopefully!

When we know what stats the OP has we'll be able to tie it down better

Mines a fully pumped system installed in 1996. It originally had a heat only boiler but we now have a system boiler installed in 2015. The main pipework is 28mm and the pipework to the radiators is 15mm, i dont know what happens to the pipework under the floor.

 

[Stuckinarut]

Maybe on older systems, with gravity HW, not on a fully-pumped system. But we'll see, hopefully!

When we know what stats the OP has we'll be able to tie it down better

My System is from 2010 (new build at the time) fully pumped and has 28mm.

 

[fixitflav]

My System is from 2010 (new build at the time) fully pumped and has 28mm.

Interesting, I'm surprised. 28mm through the pump and the auto valve(s)? I thought they were trying to reduce costs, like foisting microbore on to people.

 

[Stuckinarut]

Interesting, I'm surprised. 28mm through the pump and the auto valve(s)? I thought they were trying to reduce costs, like foisting microbore on to people.

No, it's reduced to 22mm through the pump, and dhw circuit (Coil) and 28mm heating onto 10mm microbore - maybe that's why it's 28mm?

 

[fixitflav]

No, it's reduced to 22mm through the pump, and dhw circuit (Coil) and 28mm heating onto 10mm microbore - maybe that's why it's 28mm?

Don't know what the pros on here think, but it seems odd to use 28mm and then go to 10mm microbore. Perhaps the builders had some 28mm kicking about

 

[Stuckinarut]

Don't know what the pros on here think, but it seems odd to use 28mm and then go to 10mm microbore. Perhaps the builders had some 28mm kicking about

Maybe, but they used plumbers and they did the whole estate (approx 500 houses!). Maybe it’s better flow rates? It’s concealed and perhaps reduces down before the microbore?