Do electric showers contain pumps and what exactly is a 'power shower'?

[ETAF]

how big is your hot water tank ......
when i looked into this , a small bungalow - with a small combined hot & cold water cylinder - we did not have anything like enough capacity in the tank to use a pump , and the cost to change the tank in the loft was very high.

 

[JoeyT]

For a shower using that pump you need a supply of stored hot water (HW cylinder). No mention of that so far, do you have it?

Yes, HWC right next to the shower in airing cupboard.

 

[JoeyT]

how big is your hot water tank ......
when i looked into this , a small bungalow - with a small combined hot & cold water cylinder - we did not have anything like enough capacity in the tank to use a pump , and the cost to change the tank in the loft was very high.

Cold water tank is 227l, hot water I believe is 165l. ~45l hot water for 5 minute shower is plenty for us.

 

[Johntheo5]

My definition of a power showe is one that delivers at least 10LPM at 40C so a 165L HW cylinder with a effective hot volume of 150L at 60c will deliver 250L at 40C when mixed with cold at 10C.

 

[JohnD]

My definition of a power showe is one that delivers at least 10LPM at 40C so a 165L HW cylinder with a effective hot volume of 150L at 60c will deliver 250L at 40C when mixed with cold at 10C.

Your definition, then, includes things that are not power showers, such as unvented cylinders, and my gravity feed vented cylinder with 10m head.

 

[Elkato531]

38cm from bottom of tank to the ceiling height. Currently shower head is 20cm from the ceiling but that's because we have a bath currently. Suspect it would be 40cm from the ceiling height eventually, so 78cm total from tank bottom. Is this enough?

You may need the universal (negative head) version of the shower pump. Check the maufacturer's instructions carefully. If your situation is borderline, you may be better with with the universal. Stuart Turner should be able to advise.

 

[JoeyT]

You may need the universal (negative head) version of the shower pump. Check the maufacturer's instructions carefully. If your situation is borderline, you may be better with with the universal. Stuart Turner should be able to advise.

1l/min is all it says. Will try with positive and get universal if it doesn't work as the cost difference is a lot.

 

[Johntheo5]

I have seen (600mm, 60cm or 0.6M) a few times as being the minimum height required but there is no guarantee that even your height at 78cm is sufficient as the minimum flowrate depends in the head loss through the shower head but more importantly, the head loss required to open the pump non return valves(s), can you just return the positive head pump and just pay the extra for the universal pump if necessary?.

 

[JoeyT]

I have seen (600mm, 60cm or 0.6M) a few times as being the minimum height required but there is no guarantee that even your height at 78cm is sufficient as the minimum flowrate depends in the head loss through the shower head but more importantly, the head loss required to open the pump non return valves(s), can you just return the positive head pump and just pay the extra for the universal pump if necessary?.

I can return it within 14 days.

The shower we're going for is advertised as being able to work at very low pressures due to increased water ways etc. I believe we should be good. Will report back in May when it's all installed.

 

[fixitflav]

Yes, HWC right next to the shower in airing cupboard.

That moves the goalposts. Are you now considering a pumped shower using stored H and C water? And getting rid of the existing Triton T70 GSI?

 

[JoeyT]

That moves the goalposts. Are you now considering a pumped shower using stored H and C water? And getting rid of the existing Triton T70 GSI?

That's correct. That was my intention from the start. Then to use a bar mixer with dual heads. Girlfriend's dad was insisting this is called a "power shower" which is what sparked this thread.

 

[fixitflav]

I have seen (600mm, 60cm or 0.6M) a few times as being the minimum height required but there is no guarantee that even your height at 78cm is sufficient as the minimum flowrate depends in the head loss through the shower head but more importantly, the head loss required to open the pump non return valves(s), can you just return the positive head pump and just pay the extra for the universal pump if necessary?.

Aren't you mixing up 2 things there? 0.6m as the minimum height required, I believe is for a gravity shower. If it's a pumped shower there needs to enough head to give 1 l/min, for the flow switch to start the pump, see #14. OP has a very standard set-up, so that won't be a problem (if he goes down that route).

Incidentally, I have a gravity shower with very similar head to the OP's, and while it's not a blistering experience it gives a perfectly adequate shower, better than any instantaneous electric shower I've ever used. Needs a suitable mixer and head, of course.

 

[fixitflav]

That's correct. That was my intention from the start. Then to use a bar mixer with dual heads. Girlfriend's dad was insisting this is called a "power shower" which is what sparked this thread.

OK, geddit!
I assume you'll site the pump on the same floor as the HW cylinder. I find the Stuart Turner instructions a bit confusing, it says
"2.25 Preferred pump location: The preferred pump location is at floor level next to the hot water cylinder" but doesn't show that position in Fig 2 or 3. Also unsure what they mean by "least preferred area". It doesn't say why, and you would need a shelf or something in the airing cupboard to site it in that area anyway.

 

[JoeyT]

OK, geddit!
I assume you'll site the pump on the same floor as the HW cylinder. I find the Stuart Turner instructions a bit confusing, it says
"2.25 Preferred pump location: The preferred pump location is at floor level next to the hot water cylinder" but doesn't show that position in Fig 2 or 3. Also unsure what they mean by "least preferred area". It doesn't say why, and you would need a shelf or something in the airing cupboard to site it in that area anyway.

Least preferred I assume means that you can, but probably best you didn't. Thought the same thing about not showing the preferred location, but it will go on the floor of the cupboard next to it.

 

[fixitflav]

Least preferred I assume means that you can, but probably best you didn't.

I'm curious why. definitely non-preferred from the installer's viewpoint! Are you going for the single or twin pump?