Pump at bottom of header tank in attic

[andyr123]

is this do-able and will it work? - are pumps better to 'push out' the water or better to 'pull/suck' the water through?

if you have your twin propellor pump with its 1 shaft running but 2 propellors are running but shower number 1 is not going but shower number 2 is operating would that (or the pressure but no-where to go) not ruin the propeller linked up to shower 1 ?

Or would i need to fit 2 separate single propellor pumps instead of 1 twin propellor pump at the bottom of the header tank to work it?
many thanks.

Andy.

 

[oldbutnotdead]

There's not usually much point fitting pumps to instant heat electric showers, the litres/min of acceptably hot water is pretty low (3 or 4) so minimal head is required.
Side note- if both showers are running at the same time and the dno fuse is only 60A you could be in trouble

 

[andyr123]

There's not usually much point fitting pumps to instant heat electric showers, the litres/min of acceptably hot water is pretty low (3 or 4) so minimal head is required.
Side note- if both showers are running at the same time and the dno fuse is only 60A you could be in trouble

It at my daughters house they live away from us. I am almost sure it has an Interlock or load sharing in the CU so both showers can not be used at same time.

having awful trouble with showers (both identical ones in the en-suite and main bathroom, MIRA pumped ones, with their own internal pumps in them) getting the temperature right. one minute scalding next too cold when adjusting temperature knob and poor pressure (even with built in pumps) and cold tap in bathroom and ensuite sinks and toilet trickle water pressure and its a bungalow with header tank in loft and immersion heater in cupboard - hot water taps in bathroom sinks and kitchen tap trickle too - very poor pressure , definitely needs pumps fitted I would say to increase pressure.

 

[oldbutnotdead]

Take a breath.
Relax.
Now try that post again.
Your first post indicates the showers are 9kw flash heaters.
Your second post suggests they are pumped thermostatic showers.
Which is it?
Gravity head in a bungalow will usually be low. How good is the mains water pressure?- one option worth investigating would be unvented (mains pressure) hot water cylinder. Temperature regulation on your pumped showers will be poor if cold is mains and hot is gravity.
Do they have heat options other than electricity (or do they have solar panels). If they have a gas boiler, cost per kwh is still about 30% of electric cost/kwh so worth thinking about

 

[Nige F]

if you have your twin propellor pump with its 1 shaft running but 2 propellors are running but shower number 1 is not going but shower number 2 is operating would that (or the pressure but no-where to go) not ruin the propeller linked up to shower 1 ?

View attachment 306447

View attachment 306448


Or would i need to fit 2 separate single propellor pumps instead of 1 twin propellor pump at the bottom of the header tank to work it?
many thanks.

Andy.

Something I have been asked - not sure ....as "pumping against nothing" of one impeller will only be short term . ?

 

[andyr123]

Sorry I did not explain it properly.

they are 9kw instant electric showers with built in pump - single cold pipe from header tank

Mains pressure is a bit better in the kitchen sink than the hot tap in the kitchen sink (which is fed from the immersion heater tank in the hall) - but not that much better.

 

[andyr123]

Something I have been asked - not sure ....as "pumping against nothing" of one impeller will only be short term . ?

yes I am wondering. - if you stopped both propellors but turned the pump on then you would/could burn the pump motor out but what about if you had 2 showers , 2 propellors on 1 motor shaft (twin outlet single pump) and one shower was not running then one side of the propellers would be still while the other side the propellors will be moving boosting the pressure of water to the shower that is running/working

 

[oldbutnotdead]

A pump into a pump probably isnt going to achieve a lot.
Have you checked the shower units for any filters that need cleaning/replacing? Are the shower heads clean or scaled-up?
I had no idea that pumped flash heating showers existed so apologies for that.
You'll get a much better shower from the hot water cylinder than you ever will from the flash heaters. Yes you can fit pumps to the output of a cylinder- you might need a specialised flange to prevent air being sucked in.
The pump from the header tank- try it if you want. It would be highly possible to tee off the pump outputs a pair of returns into the header tank (fit with adjustable pressure relief valves, set them by trial and error, make sure they can adjust down to below the max output pressure of the pump).

 

[andyr123]

these are their ones in the main bathroom and en-suite . Yep I inspected and cleaned the filters at the bottom (although there was nothing to clean really they were spotless) and the shower heads were nice and clean (not really hard water where they are) .

Mira Elite SE Pumped Electric Shower - 9.8kW White & Chrome - 1.1941.001

Mira Elite SE Pumped Electric Shower - 9.8kW White & Chrome 1.1941.001. Lowest price guaranteed. In stock: Delivery Next Day. Rated 5.0/5.

www.plumbworld.co.uk

could change them for immersion fed non instantaneous pumped but along with buying new showers then i would have to plumb in extra pipes from the immersion tank cylinder to the showers that will be awkward and messy.

Be handy to try the pump at the bottom of the header tank (more room to move) or stick a pump (or 2) in the airing cupboard but its a bit tighter space there where the pipes are.

 

[Johntheo5]

It at my daughters house they live away from us. I am almost sure it has an Interlock or load sharing in the CU so both showers can not be used at same time.

having awful trouble with showers (both identical ones in the en-suite and main bathroom, MIRA pumped ones, with their own internal pumps in them) getting the temperature right. one minute scalding next too cold when adjusting temperature knob and poor pressure (even with built in pumps) and cold tap in bathroom and ensuite sinks and toilet trickle water pressure and its a bungalow with header tank in loft and immersion heater in cupboard - hot water taps in bathroom sinks and kitchen tap trickle too - very poor pressure , definitely needs pumps fitted I would say to increase pressure.

Any pumped electric shower will supply ample pressure from its integral pump, a 9.8kw will probably give up to or > 10LPM if temperature control is turned to fully cold. Even if you only require a showering temperature of 38C from a (now) mains temp of 20C, then the flowrate required is 7.8LPM, if the temperature is hot/cold then the flowrate is only 5.0LPM or less as the TCO (thermal cut out) operates at 48C on those showers, I would test the max flowrate by turning the temperature control to fully cold then hold a bucket under the shower head for exactly 1 minute and measure it into a 1 litre milk bottle or whatever.

Re your query of burning out a booster pump, very unlikely but you might damage the pump seals, unlikely in a cold only twin pump, (which doesn't make sense anyhow, you would install a single impeller pump with sufficient capacity to serve both showers), the question is often posed where a "twin" pump (whole house) suppying both hot & cold is running for prolonged periods using only say the cold to wash a car or whatever, Stuart Turner, I think , say that its not a problem for their brass bodied pumps but I wouldn't care to put it to the test.

 

[oldbutnotdead]

As @Johntheo5 on the flowrate test. It is possible that the feed pipes to the showers are full of crud from the cold water tank or intermittent bits of dead rat are bunging the pipe occasionally- well worth a look anyway.

 

[andyr123]

I would test the max flowrate by turning the temperature control to fully cold then hold a bucket under the shower head for exactly 1 minute and measure it into a 1 litre milk bottle or whatever.

thats a good idea thanks

 

[andyr123]

As @Johntheo5 on the flowrate test. It is possible that the feed pipes to the showers are full of crud from the cold water tank or intermittent bits of dead rat are bunging the pipe occasionally- well worth a look anyway.

So, a test of taking front cover off the shower, undo the compression joint and run the water into a bucket and measure the amount of litres per minute the water is flowing from the pipe from the header tank then look at the spec's for the shower of required minimum input and check that it meets that?
also, showers have in their spec's minimum BAR for them to work properly , how would i be able to measure the BAR pressure of the pipe going into the shower unit effectively as well as the litres per minute?

I cannot be 100% sure but rather than anything blocking the pipes from the header tank I still think there is not a good enough head of water coming from the header tank personally myself and seeing as its a bungalow and that the header tank is up in the attic above the main bathroom that it just hasnt the pressure / enough pressure for the input required for the showers . i could be wrong though.

 

[Lower]

What size pipe feeds the showers? Pressure and flow rate are two different things.

If you don't have much head pressure (ie not much fall between the tank and the outlet) you can compensate by having a larger bore pipe so that you have better flow for the same head pressure.

 

[Johntheo5]

Do the simple test first, just turn the temperature setting to its coldest, start the shower and then just hold the bucket under the showerhead as is and measure it.