Wits End – Unbalanced water supply causing tap mixer issues

Hi,

Any help or advice on the following matter would be greatly appreciated. We recently had a leak in our cold water tank and had the plumbers replace it, as part of the work they changed the cold water (from the tank) to the mains supply (the tank they installed is smaller than the old one) and despite assurances from them that there would be no issues in doing this we now have unbalanced supplies which is making it very difficult to regulate the temperature in the shower (via a basic tap/mixer); either the hot is on or the cold. Previously we could combine the two which would result in reasonably pressure and flow from the shower, now because the shower is pretty much only hot or cold the pressure is not very good. The plumbers involved then fitted a pressure reducing valve to the cold and a non return valve to the hot (at extra cost I might add) which allowed us to reduce the flow of the cold (not sure about the pressure to be honest) but this has not solved the problem. The plumbers now reckon that I need a pump to increase the hot water pressure; more cost. I have decided that if I do need to do this then I won’t be using these plumbers as they are the ones who have gotten me into this mess in the first place, but before contracting another plumber I was wondering if anyone knows if there are taps I could get (and install myself) which do a reasonable job of mixing unbalanced supplies (as an FYI, the actual flow of the hot is now greater than the cold, pressure is obviously not though)

I was considering the following ones:

http://www.screwfix.com/prods/91379...ower-Mixer;jsessionid=2AO3HBGZCNBTECSTHZPCFFA

since the pressure out of the spout is good and the temperature can be regulated (out of the spout).

Any advice would be greatly appreciated.

Thanks,
David

The solution is simple really.
Change it back to gravity supply !. Whilst doing so you could consider raising the cold storage cistern to acheive more pressure.

you need equal pressure hot and colds. both should be tank OR mains fed. A pressure reducing valve on the cold main may cure the problem but is treating the symtom and not the fault.

Thanks for the reply guys, the thing is though the area where the water tank is is restricted and this is why a smaller tank was put in, I am not sure if it is of sufficient size to feed both the hot and the cold !

I am just trying to weigh up the options and come up with the least expensive acceptable one given that I have already spent four hundred pounds and am nearly in a worse place than when all of this started !

Surley some taps are better at mixing unbalanced supplies than others, I haven't measured the pressure coming out of the taps (not sure how to, to be honest) but I don't think there is a huge difference, although I do realise that flow and pressure are not the same thing. As I said, the flow/pressure/temperature out of the spout is fine hence I am wondering if a spout type of shower mixer like the one mentioned would be better then the basic mixer tap I have at the moment.

Cheers,
David

djharte said:

assurances from them that there would be no issues

Click to expand...

they lied.

So no mixer tap setup will resolve my problem then ?

Apart from getting another tank installed what do you reckon my best option is? Hook the hot water supply up to a pump?

Cheers,
David

a pump will improve flow on the hot water but not increase it to mains pressure.

But they did put a pressure reducing valve on the cold (and a non return valve on the hot) and the pressure appears to be pretty close to the hot but it is still not mixing properly. The thing is though they also replaced the taps a few days after changing the cold to the mains and I am reasonably sure I didn't have this issue with the old taps (which have since been thrown out) hence I wonder if some taps are better than others in dealing with this, especially as I said the pressure doesn't appear to be all that different between the hot and cold.

Before I go out and buy new taps then (the ones with the shower connection near the spout) can someone please let me know if I am waisting my time and will still have the same issue (with the new taps) ....

Thanks,
David

you could try a pressure equalising valve (basically constantly matches the pressure of hot and cold) - Plumbworld sell them http://www.plumbworld.co.uk/pressure-equalising-valve-344-230.

I'm in the process of trying to do exactly the same thing with my bath mixer. The valve seems to work reasonably well as long as you've got a few metres of head pressure on the hot flow.

hi the cold feed should never have been fitted to the mains for the shower anyway both the hot and cold should be fed from a storage tank because if you were in the shower and someone turned on the cold mains you would get scalded with the hot water alone but if its on a storage tank no other feeds are allowed to be taken from it , then you have an equal pressure and flow then if someone opens a hot tap you will only get a cold shower and that will not harm you, so my advice is to get it put back to storage , if you did get scalded you would have a claim against the plumbers as what they have done is not legal

To be honest, even when the hot and cold came from the storage tank we were still susceptible to that problem, but given that it is a one bedroom flat I am not too concerned about that, although your point is well made.

The difference in pressure between the hot and cold is not that high, in that I can stop both with by thumb however obviously the cold is higher since it is stopping the hot. The thing is though that I can regulate the water out of the spout fine but I do understand that if pressure is applied at the spout then the hot and cold will still end up fighting. Outside of shelling out lots more cash I am hoping that a "dual flow" mixer tap may resolve the issue to an acceptable level (since the hot and cold would be separated until they enter the hose)... so the big question is, does anyone know any manufacturer which sells dual flow bathroom mixer taps, I did find this but am not sure:

http://www.heatandplumb.com/acatalog/Waterways_CD_Bath__Shower_Mixer.html#aPCPKAT033

Or should I just call the plumbers? (in fact I did do this and am waiting for the good one to get back to me).

Thanks