Low hot water pressure

[kevplumb]

na probs marra

 

[Lurker]

A pump will not be suitable with a combination tank. The Header usually empties faster than it is filled.
You need a double check valve on the cold supply to the bath mixer and a single check valve on the hot, double if it is pumped.

In other words forget the whole idea of supplying a mixer from unbalanced supplies.

 

[JonathanTaylor]

Next to the hot water cylinder on the first floor are two valves. I understand that these two valves control whether the water going into the main hot cylinder is fed from the solar system (the previous owner has kindly written instructions on how to turn the supply off on the wall next to the cylinder). I therefore think the solar system is redundent, as the valves are in the 'off' position.

I can isolate all cold taps by turning off the main stop cock in the kitchen (this also prevents the first floor hot water cylinder from re-filling after hot water is drained). I am therefore guessing I have mains fed cold water to all taps, and the first floor hot water cylinder (providing the solar system valves are switched off), and that all the gear in the loft is redundent.

Can I (should I?)fit a pump to this system?
I am not familiar with the "double check valve" and "single check valve" Lurker mentioned. Would a single check valve on the hot water supply pipe in the bathroom fix the problem? Bearing in mind I get a poor hot supply, even if the cold is turned off.

 

[JonathanTaylor]

No pics yet, so I'll have another go at this myself.

 

[brumylad]

I would run your hot tap and see if the upper part of the copper cylinder in the loft starts to fill from the float valve

 

[JonathanTaylor]

It does. I've followed all the pipe work, and the lower part of the cylinder in the loft empties into the base of the cylinder on the first floor. Mains cold then replenishes into the top half of the cylinder in the loft. The valves on the first floor are used to direct water from the bottom half of the loft cylinder either:
1. To replenish cold into the first floor cylinder.
2. Directly to hot taps, bypassing first floor cylinder (this woudl be used if the solar system was in operation).

The solar equipment upstairs is operated by a pump, which is not plugged in.

So the good news is I think I can fit a pump. The bad news is, the loft cylinder is probably too small so will need replacing. Also, the bathroom cold taps are currently fed by a spur off the rising main (it passes through the bathroom before getting to the loft cylinder). Therefore, I'll need to run gravity fed cold back from the tank through a new pump in the airing cupboard to the bathroom. Additionally, the whole house's hot water is fed through a single pipe from the airing cupboard, so I think I will also need a "whole house pump". I'm thinking of a SALAMANDER RIGHT PUMPS: 2.25bar Twin Whole House Pump. Twin because I want another shower fitted in an en-suite in the future.

 

[bobxx]

Hi
You say old tap working ok so pressure must be ok.
Could be faulty mixer taps try reversing pipes to see if hot comes out ok on cold side if so spinldle not operatig properly on "hot"either return mixer to supplier or take it apart and repair.

 

[JonathanTaylor]

Hi Bob,

I have tried reversing the hot and cold. Unfortunately, the pressure was just as bad. So I don't think it is a specific fault with the tap. I guess it could just be the way that it has been designed. Roca (tap manufacturer) said it needs at least 2 bar pressure to operate.

 

[bobxx]

Does mixer taps have shower attachment.If not why not change them.Save a lot of hastle.

 

[JonathanTaylor]

Hi Bob,

Unfortunately it does have shower attachment and a seperate spout. So I have four holes drilled in the top of the bath to suit this particular tap setup.