low hot water pressure All aspects of plumbing questions and answers, help, tips and information

[gilly120]

i have installed an en suite into the house i replaced my hotwater tank which was in my loft and fitted a 3 bar pump to increase pressure to the shower since new tank was installed which was the same size as old tank i have a poor hot water pressure through house when i have shower running the hotter you put the thermastat at the weaker the pressure and if u put shower thermastat to cold you get the full 3 bar pressure through shower pump seems to be running fine what would cause this

many thanks chris

[EyeTry]

You say you fitted a new hot water tank the same size as the old - so the only change would appear to be the fitting of a pumped shower... .

If you were installing an electric shower you would have the choice of several power ratings - at the lower end your demand for hot shower water would mean the flow would drop so that the heating element in the mini-hot-water tank had time to heat it to whatever temperature setting. A higher end unit would have a bigger element and therefore heat the water quicker and therefore allow you to maintain the set temperature but at a greater flow through.

You don`t say what size pipe feeds the pump (then the shower) and whether it is run as a separate feed off the hot water tank outlet OR is just taken as a tee-off with the original feed continuing to the bathroom and basin then kitchen tap. If it is part of the general circuit then I would expect the pump to almost suck the flow away from the other connections and thus reduce their pressure.

I can`t see why the hot water temperature would affect the flow because the boiler would be trying to heat the water in the tank and if you ran the shower before you had a tank of hot water you would just get the flow but at cold or luke warm temperature. Or is your system one of the "hot water on demand" systems where turning a hot tap on creates a water flow and that triggers the boiler part to fire and heat water in the integral hot water tank. I don`t think that would be sufficient for a pumped shower system - it would be similar to the small electric shower mentioned above.

Presume you realise that power showers push more water out in a given time so water usage and fuel bills rise...

Hmmm... EyeTry

[gilly120]

hi

thanks for reply and you seem to know what your talking about.i have cured the low hot water pressure in taps through house was an airlock in system so there working fine now.the problem still persists with the low pressure when hot water comes through pump im not sure on size of pipework but when water pumped through cold it works fine so must be right size of pipework.the set up is rain shower from celing and a wall shower on wall you can switch between the 2 with a ghrohe rapido shower valve the pump is a 3 bar salamander pump and it does kick in and checked all valves are opened fully could it be the pump is not getting fed with enough water?


many thanks chris



[quote="EyeTry"]You say you fitted a new hot water tank the same size as the old - so the only change would appear to be the fitting of a pumped shower... .

If you were installing an electric shower you would have the choice of several power ratings - at the lower end your demand for hot shower water would mean the flow would drop so that the heating element in the mini-hot-water tank had time to heat it to whatever temperature setting. A higher end unit would have a bigger element and therefore heat the water quicker and therefore allow you to maintain the set temperature but at a greater flow through.

You don`t say what size pipe feeds the pump (then the shower) and whether it is run as a separate feed off the hot water tank outlet OR is just taken as a tee-off with the original feed continuing to the bathroom and basin then kitchen tap. If it is part of the general circuit then I would expect the pump to almost suck the flow away from the other connections and thus reduce their pressure.

I can`t see why the hot water temperature would affect the flow because the boiler would be trying to heat the water in the tank and if you ran the shower before you had a tank of hot water you would just get the flow but at cold or luke warm temperature. Or is your system one of the "hot water on demand" systems where turning a hot tap on creates a water flow and that triggers the boiler part to fire and heat water in the integral hot water tank. I don`t think that would be sufficient for a pumped shower system - it would be similar to the small electric shower mentioned above.

Presume you realise that power showers push more water out in a given time so water usage and fuel bills rise...

Hmmm... EyeTry[/quote]

[EyeTry]

I must have mentioned possible airlocks to three other enquirers but didn`t to yours.... aghh. Never mind you got there yourself, well done.

Grohe do a manual or a thermostatic system so I wonder if the hot supply is insufficient - a bit like a fireman using his hose on a fire but there`s just a garden hose refilling the tender... it runs out of pressure and provides all cold water.

As it is a new installation have you got the connections the correct way round? I think (looking at it face on) the connections are Bath / Top Left; Shower / Top Right; Hot In / Left; Cold In / Right; Body sprays / Bottom but the details should be confirmed via your fitting instructions not me.

look for Grohe`s website for more info.
Good luck, EyeTry

[EyeTry]

Hi Chris, I got Grohe`s tel no. and that useful video clip after a google search and included them in previous response but it seems this site has to filter such details out (impartiality etc). Regards EyeTry