No hot water from new pull-out kitchen mixer tap

[Kiwibrox]

Had to replace our old simple mixer tap because it started to leak so bought a shiny new mixer with pull-out hose. All the other hot taps in the house upstairs and down are ok but only a dribble from new mixer in kitchen. If the cold is turned on then tank in loft overflows so I suspect that hot and cold water supplies too unbalanced.

Can I fit a non-return value to hot supply to fix this or do I need a pump to boost hot water pressure.

 

[HERTS P&D]

Cheap tap,................. a non return valve will work on the hot supply buy it will also reduce the pressure.

Andy

 

[Kiwibrox]

Cheap tap,................. a non return valve will work on the hot supply buy it will also reduce the pressure.

Andy

I think there are two problems, a very big mismatch in pressure between hot & cold and a very small feed into the tap as cold isn't that great either compared to old tap. I think we need a simpler design for a low pressure hot water system, pity tap actually looks really nice.

 

[Whitespirit66]

If you have isolation valves fitted, removing these can buy you some more flow. If the hot is that bad though, this may not be enough.

If the tap has a single mixer and or ceramic discs, these work against low flow from gravity systems. Even the hose on this model is increasing flow resistance.

A mixer with seperate hot and cold controls would be a better bet. Proper washered valves even better.

 

[StephenW]

I had one of these taps for a while. Although mine was designed for gravity-fed hot it did restrict the flow maybe by about 50% compared to a normal tap.
I'm a bit surprised that the cold is forcing the hot back up the pipe. I thought kitchen mixer taps, especially on mains cold/gravity hot, were not meant to mix the water until it finally emerged into air and so the spout is often two separate pipes inside. But a hose would negate this.
I think if you fitted a non-return valve, the extra pressure reduction would mean you possibly wouldn't get more than a drip coming out.

 

[Kiwibrox]

I'm a bit surprised that the cold is forcing the hot back up the pipe.

No doubt about the reverse feed, turn on the cold and you get low flow, turn on hot and flow reduces yet you hear more water flowing and a few minutes later water starts coming out of tank overflow. Off to buy a new tap...

At least I know that tank overflow isn't blocked ;(