TMV hot or cold, but not both?

[ob0t]

I've got a Hudson Reed sequential thermostatic mixer tap and I can't seem to get hot and cold to mix right. With both supplies connected I get only cold water (hot supply doesn't seem to engage at all, even if I reduce the cold flow by half-turning the isolating valve). If I disconnect the cold supply completely I can get hot water out, but only at a trickle. There's a grub screw to adjust the max temperature, and that's dialled up to the max.

Does anyone have any pointers? Mains pressure is within the stated operating range of the unit, and hot water is supplied via a combi unit.

Thanks in advance!

 

[buck51]

Piped up back to front, hot to cold/ cold to hot

 

[ob0t]

thought that too, and I double checked with the diagrams so make sure. Swapping them around makes things worse - turn the tap on (to a cold setting) and I get a decent flow of hot water, which gradually slows down to a stop, and following through to a hot setting gives me cold water.

 

[swbjackson]

What do you mean by a combi unit? Combination boiler? Combination cylinder? This sort of problem generally happens when the cold is on the main and the hot tank fed.

 

[ob0t]

it's a combi boiler

 

[Charnwood]

Does it need adjusting? A lot of blending devices have to be set at the commissioning stage.