Shower pump won't switch on when hot water is required

Hi,

We had a Techflow 3 bar shower pump fitted a couple of months ago. The pump is fitted at floor level of the first floor about 8 metres from the hot water tank. It supplies an ensuite bathroom. The header tank is above the hot water tank in the loft.

When you try to switch the shower on (preset to hot) you get no water or pump for about 90 seconds. Once the pump does start the shower works fine.
The shower works from a Hans Grohe Ibox and has a rain head along with two pencil handsets, fitted at waist height. If I switch the diverter valve to the handsets I get water and pump on immediately.

In addition, the bath taps will switch on the pump immediately, however the basins suffer the same problem, cold water switches on the pump immediately but if you ask for hot, there is a long delay before the pump switches on and you get water.

There are two manual air valves on the hot and cold pipes going into the pump and I have checked these and there is no air.

So I just wonder if anyone has any ideas as to what is preventing the pump from switching on when the basins or shower ask for hot water?

Any help or ideas would be gratefully received.

Thanks for your help!!!

The head is not great enough to get through the ibox and activate the pump.

You should try a negative head pump.

Hi,

Sorry to ask about this again, but we still have the problem. As an update, we had Techflow out to look at the pump. They checked the installation and head etc. which was all fine and so exchanged the pump. However, sadly, this has made no difference to the problem, so we are still stumped as to what the problem is.

Any ideas please?

Thanks ever so much!!

how high is the tank in the loft? is it sat on the ceiling joists or raised high up into the roof? if the distance between the tank in the loft and the rain head is not eniugh then the flow of water will not activate the flow switch on the pump as quick.

re the basins, are they piped in flexible tap connectors or 10mm pipe at all?
the bore on these is very small and will again restrict the flow so the flowswitch is not activated quickly enough.

it could be a sticky flow switch, the rain head could need cleaning. without being there its difficult. you might even need to lift the tank in the loft.

you need to remove the non return valves fitted on the hot and cold inlets on the i-box.
all i-box showers come fitted with non return valves they should be removed when fitted on balanced supply's from un-vented systems and balanced pumped supply's.


Steve

Thank you so much for some ideas, which I will definitely investigate!

The cold water tank in the loft is 8.8 foot above the pump (taken from Techflow engineer report.) the pump is at floor level of the bathroom, so the shower head is probably six foot or so above the pump.

I am not sure about the pipework that runs to the basins, but I will check. I do know that the bathroom fitter reduced the flow to the basin taps as they were causing too much splashback, so maybe this is not helping the problem. I might see if the flow to the basins can be diverted so as to avoid using the pump, as it really isn't necessary on the basins.

Regarding the Ibox, I will check with the bathroom fitter about the non return valves; this could be the answer. They are due to come back in January, as they didn't fit the wet floor former properly and are having to redo the whole thing! We haven't been able to use the shower since October; (bathroom was fitted in June,) as they tried to deny liability.

Thank you again for these suggestions, they are soooo helpful to someone like me!!!

We fit the Stuart & Turner negative head pump with Hans Grohe Iboxs (or convert to un-vented) never had a problem see link below.

http://www.showerdoc.com/showers/st...oon-Universal-3-0-bar-Twin---Shower-Pump?pg=2

Just to sum it up, you need to imrove the flow before the pump starts as your "head" is quite low - I make it that your tank is only 2.8 feet above the shower head (from your figures above). Reduce the resistance - take out any reducers, one way valves and any narrow flexies. You cat test the unpowered flow by switching off the power to the shower and see what you get.

Our tank is about 1M off the loft floor on a raised platform and have never had any problems with power showers.


Just a householder

Once again, thank you very much!

It is clear that it is a flow problem, or rather, lack of it. I wish we had fitted a negative head pump, the pump was supplied by the plumber without any discussion. I am wise after the event!

I am going to look at all the suggestions and maybe using a combination of these we will hopefully solve the problem. I did have a look at the tank in the loft today and it is about two foot off the floor, so potentially we could raise that another couple of feet, which should help a little.

thank you again, everyone's comments have really helped!!!

Did you remove the non return valves as suggested? They do add a resistance to the flow rate.

As an aside, how did you move from the installers denying liability to the position that they are now going to relay it?

Tony

To answer your questions, haven't had the non return valves changed yet, but am definitely going to get this done, as it sounds like an easy one to start with. I am guessing I can't do this myself and need the bathroom fitter to do it? ( I am only a lowly female, so my skills are limited

In answer to your other question, the bathroom company have been dreadful. They put all blame on our floor joists which we have now found out are if anything oversized for the span. We were lucky in that the ceiling below had downlighters and by removing one, we could see the underside of the wet floor deck. I then examined the installation instructions on the manufacturers website and along with the carpenter we discovered they had only used 12 mm ply under the deck. Hence movement in the floor, which had caused the grout to crack in the shower floor above. They still denied liability and advised I had to cut a hole in the ceiling and then they would double up the ply for me to replaster the ceiling (at our expense.)

The manufacturer, who were extremely helpful, suggested someone who would come and produce an independant report, with photographs and required remedial works. This was really helpful, though we still had to threaten legal action before they agreed to take up the shower floor.

We have not had the use of the shower since October. At present, they have removed the deck, added more ply and refitted the deck and wet floor membrane, but have broken the underfloor heating wire in the process about five times. So we are waiting on their proposal to resolve this.

We spent £20,000 on this bathroom, so I am really disappointed in the service received. If I hadn't been so persistant in finding out how you should fit a wet room and what they had and hadn't done, we could never have proven their liability.

It has been a long hard slog and I now feel I could almost fit a wet room myself!

Thanks again for all your help!!!