Increase hot water pressure, positive or negative pump?

[Mike Buck]

Morning Boys, and girls

so we've just had new bathrooms fitted and our hot water flow is rubbish, the fitter said that the pressure didn't even register on his gauge. I'm considering installing a pump just for the hot water system, but NOT the showers, as they have their own pumps. the hot water tank is on the 1st floor in the airing cupboard, allour taps are mixer taps. I spoke to Salamander and they recommended a negative pump, but i'm not sure. I get that it depends how the water flows, but alot of time the question comes up for showers when there is a raise in the pipes to the shower head, mine is just tapes.

So do you guys still think i need a negative? the pump will go in the airing cupboard next to the hot water tank.

Cheers

Mike

 

[Dan Robinson]

I wouldn't use a salamander for a start.

Look in the manual of the pump you are looking at, and see if the static head is correct. I would have thought a positive head Stuart Turner would be fine.

 

[oldbuffer]

If the flow from the bathroom cold taps is good, it suggests the hot taps are fed from the hot water cylinder, but the cold taps are mains fed. The pressure of the hot water is determined by the height of the cold water storage cistern, which is presumably in the loft above the 1st floor.

If you try and use a pump to improve the hot water flow, you'll have to try and balance the pressure of the pump output to the mains pressure, or you run the risk of backflow under certain conditions. It does sound as if a positive head pump would be sufficient, and I personally like the Stuart Turner ones.

A better solution might be to convert the tap cold supplies to tank fed, and use a normal hot and cold pump to improve the pressure, and hence the flow, to both. However, this could involve a fair amount of extra pipework.

It also sounds as if the taps are designed for high pressure, and are probably wrong for the system you have.

 

[garyo]

An unvented cylinder is your other option if your cold pressure is good enough. Completely different set of considerations though.