Shower Pump Plumbing (Groan!)

[Big Al]

Ok. I know there are countless discussion topics on this (I've read them!) but I'm after a little confirmation before I go cutting into my pipework.

I am fitting a new shower to the bathroom with a separate pump. After much deliberation, I have run a dedicated 22mm cold feed from my CW cistern in the loft into my airing cupboard on the 1st floor. The twin input pump is to be placed on the floor in the cupboard alongside the HW tank. I now need to supply hot water from the HW tank.

Wishing to avoid a Essex / Wessex / Surrey or any fiddling with flanges on the HW tank, I could T into the 22mm vertical pipe that is the vent and HW supply for the bath. This `should` be ok. However, it would be infinitely easier for me to T into the horizontal coming from the HW tank that connects to the vent pipe / bath supply. If I brought a downwards pipe from this horizontal to the pump would all be ok or am I asking for trouble?

Kind regards

Alun

[Doctor Evil]

Alun, Tee in as close as possible to the hot water cylinder. On the vertical vent pipe insert a piece of 28mm pipe for as long as you can. When the pump kicks in it take the line of least resistance. This means that the water in the open vent pipe is drawn into the pump. If there is enough water in that pipe then the pump will use this initially (not running dry), and then take water from the cylinder as the system stabilises after the initial pump surge.

You should have run 28mm from the cold water tank to the cylinder. As already have a 22mm pipe, you could take another pipe off the cold water tank and run this to the cylinder. Two 22mm pipes in parallel. If there is another connection at the bottom of the cylinder use this. If not then fit a 28mm cylinder connector and tee the two 22mm pipes into this. have a full bore stop-c*ck on each 22mm pipe.

Using a 22mm cylinder cold feed means that when the pumps is running, if hot water is drawn off elsewhere, it will rob the cylinder and pump of water, with the pumps taking the line of least resistance and drawing down from the open vent, then running dry.

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[Big Al]

Hi!

Many thanks for the reply. I think I am ok with the feed from the CW cistern to the HW tank as it is already 28mm. The pipe I have added is a dedicated 22mm from CW cistern to the pump.

Adding a length of 28mm to the vent pipe should be ok. I guess this means that there is more water held above the pump and hence the pump is less likely to suck it all through?

Re - `Tee as close as possible to the HW cylinder`. Does that mean that there should be no difference teeing into the horizontal section than there is teeing into the vertical bath / vent pipe? Alun

[Ian_m]

Doesn't matter what size pipe you are using, the pump will suck the water out the vent pipe and pull air through, using a wider pipe will just delay the air inrush by a couple of milliseconds.... been there done that.....

Ended up doing "a propper job" with a Warix flange on top of tank after a*sing around bodging the vent. Did you ever wonder why all the shower pump fitting instructions say you must use a flange ? well they are right use flange.

If I was fitting again I would use an Essex flange, fitted/cut into the side of the tank to save all the messing around and re-routing of the vent pipe feed with the Warix flange (not the vent comes from the side of the flange not the top, meaning re-arrangement of vent piping is required). Techflow do a flange (Techflange) that can easily be retrofitted to a tank.

Anyway with correct flange (and Techflow pump

shower was wonderful and absolutely no trapped air...

[Christian McArdle]

Actually, if you get enough water flow into the bottom of the cylinder, you can get it to work without a flange. I managed with my old system and that was with an immense flow rate too, (i.e. 50lpm).

The key is not the vent. It is getting water into the bottom of that cylinder. Short, wide, unshared, flowed bended and with no constricting valves is the order of the day.

Even with a flange, you'll start sucking air eventually if you don't sort the cold water supply to the cylinder.

Christian.

[mungoh]

cylinder, you

Hi Christian, I'm following this thread because of a looming en-suite installation.

In my circumstance, I have a 50 gallon cold cistern in the loft feeding my hot water cylinder in the floor below (approximately eight feet down). Supply is via 28mm copper pipework all the way into the hot water cylinder, the route of this supply pipe is "continually rising" or level sometimes (what I mean is there are no down-then-ups in the topology).

Out the top of my hot cylinder I plumbed the outlet in 28mm copper, which gracefully (45 degree elbow) slopes down to floor level where the

28mm pipework ends in an compression T piece with 22mm pipework either side. As my mind pictures a plan view of this setup, the left side of the T wanders off in 22mm copper to the bathroom to supply the existing gravity shower, bath and basin. The right side of the T comes along for about two or three feet in 22mm copper then dives downward to the ground floor. All this 22mm pipework safely enclosed in the eaves of my upstairs.

New en-suite planned for the right side of the house (existing shower and bath at the left gable end of the house but is downstairs). The en-suite (obviously) is in the upstairs, off the master bedroom.

Since the eaves is about two feet wide, I'd prefer not to site the new pump in the middle of the (guessed) ten metres run of the length of the house because it will be a bl**dy nuisance on those ocassions when I have to crawl along there to do maintenance. So I'd like to site my new pump in the eaves but at the right hand gable end.

Present plan (and this is where I'd be grateful for advice) is to plumb the descending 28mm pipe from the hot tank such that when it hits the T piece and turns RIGHT it will still be in 28mm. Then two feet later as it turns down for the downstairs I will install a 22mm downfall plus a 22mm end to carry the pipe further right for about 4 or 5 metres before it meets the pump.

Is this a bad idea? Will the pump hate to be miles away from the tank? Will the use of fat pipes override this need? Will I still need some sort of flange even though the supply to the hot tank and the output are both

28mm fat? Ought I to make the final 4 or 5 metre run in 28mm after all?

Any experiences gratefully accepted; thanks in advance.

Mungo

[Christian McArdle]

I wouldn't use 28mm from the cylinder outlet, particularly when pumped. All it does it mean it takes longer for actual hot water to come out at the end. I'd have the pump next to the cylinder and run either 15mm (for a shower room) or 22mm (for a bathroom) from there. I would even consider using 15mm to a bathroom. It is the connection between the cold tank and the bottom of the hot water cylinder that would be seriously helped by a short as possible

28mm connection.

Basically, from the top of the cylinder, you should have 22mm going up to the vent over the tank. Then 22mm should be teed off straight into the pump. The outlet from the pump can be 22mm or 15mm to the rest of the house. Any desired gravity outlet (i.e. kitchen sink) can come off before the pump. I'd use a single impellor pump for this, and mains cold, if the mains is good enough.

Christian.

[Christian McArdle]

You should note by "should", I mean if it is not possible to install a flange, which would be superior.

Christian.

[BigWallop]

I take it the hot water tank has been plumbed with a combined expansion and draw off pipework scheme, by the way you describe it. If you can take outlets from the hot outlet as low down to the floor as you can, then you won't have any problems of dragging air into your pump from the expansion pipe.

Looking at the pipework you have, you should be seeing a 22 mm Equal TEE with the branch pointing toward the top of the hot water cylinder, right?

The straight through part of the TEE is pointing vertically straight up and down, correct?

The pipework coming from the lower connection, toward the floor, is the supply to the water system for the rest of the house, is this right?

So, what you need is a plan to supply the pump with constant hot water, but you also need to keep the rest of the house supplied from the same point, right?

If all the above have been answered with a "Yes", then you really only need to place another 22 mm TEE fitting to the section of pipe that drops toward the floor. You will be better off keeping it as low to the floor as you possibly can, but the pump is only supplying one shower that is presumably very close to where the pump is sited. Let's say, within a couple of metres?

You're running the feed pipes for the shower head in 15 mm, for both, aren't you?

If this is also a "Yes" answer, then the 22 mm pipework for the twin pump will be well able to supply the shower without problems.

I don't understand why you had to run a separate 22 mm feed from the cold tank, when you could have drawn you cold supply for the pump off the same supply that feeds the hot water tank. Both pipes would have been in the place, and would have been less hassle, in my way of thinking, than doing all that un-necessary work.

Pipes of 22 mm diameter will quite happily supply three 15 mm diameter pipes without any major losses. You would have two 22 mm pipes to the pump, and each of these pipes are only supplying one 15 mm pipe each on the outlet of the pump. The difference in the flow rate of the water between the supply and outlet sides of the pump would be minimal. All you need the pump to do is keep a constant head of water to keep the shower head flowing nicely.

[tarquinlinbin]

I would seriously suggest that you do need to Essex flange it,preferably a flange with no internal shoulder stop so that the pipe can be fed into the centre of the cylinder.

joe

[Big Al]

Hi BigWallop

Many thanks for this - you've described my pipework pretty accurately.

I've put the dedicated 22mm cold feed for the pump to be sure that no other cold water draw will impact the shower. The other options were to take a feed from the 22mm cold for the bath or, as you suggest, the

28mm feed for the HW tank. Neither of these seem suitable to me as if I take from the bath feed I run the risk of impacting / being impacted by someone running a bath at the same time (it happens!) and if I take from the cold feed to the HW tank I am directly impacting the hot water flow (I think..).

The main reason for my question is that whilst I appreciate that a flange of some description will minimize the likelihood of the pump drawing air, I don't wish to fit one if I can avoid it. Tapping into the HW pipe as low down as possible makes a lot of sense but a further complication is that my existing pipes are butted up against a wall. Cutting into them will be a pain in the a*$e. If there are no obvious clangers with cutting into the HW pipe just before the TEE of the expansion / draw off pipe then my life is much easier I think.

[mungoh]

Hi Christian, Ta for the info. Apologies to "Big Al" for hijacking his thread.

Mungo

[Christian McArdle]

The problem there is that this will reduce the flow into the bottom of the cylinder, making it very likely that the hot side of the pump will suck air.

Christian.

[Doctor Evil]

Adding a length of 28mm to the vent pipe should be ok. I guess this means that there is more water held above the pump and hence the pump is less likely to suck it all through? "

Yep.

" Re - `Tee as close as possible to the HW cylinder`. Does that mean that there should be no difference teeing into the horizontal section than there is teeing into the vertical bath / vent pipe? "

The closer the pump tee is to the cylinders hot water draw-off, th better

-- Doctor Evil

[Doctor Evil]

Many thanks for the reply. I think I am ok with the feed from th CW cistern to the HW tank as it is already 28mm. The pipe I have adde is a dedicated 22mm from CW cistern to the pump.

Adding a length of 28mm to the vent pipe should be ok. I guess this means that there is more water held above the pump and hence th pump is less likely to suck it all through?

Re - `Tee as close as possible to the HW cylinder`. Does that mean that there should be no difference teeing into the horizonta section than there is teeing into the vertical bath / vent pipe?

Doesn't matter what size pipe you are using, the pump will suck th water out the vent pipe and pull air through, using a wider pipe will jus delay the air inrush by a couple of milliseconds.... been there don that.....

Ended up doing "a propper job" with a Warix flange on top of tan after a*sing around bodging the vent. Did you ever wonder why all th shower pump fitting instructions say you must use a flange ? well they are righ use flange.

If I was fitting again I would use an Essex flange, fitted/cut int the side of the tank "

If you were doing it again it is best to use one of these, and no pump A shower coil cylinder with a quick recovery coil, killing many bird with one stone:

- mains pressure shower

- quick recovery means cheaper gas bills

- quick recovery means the cylinder is effectively larger as it wil produce more hot water.

- quiet (no noisy pumps).

- shower coil is simple

- shower coil is reliable,

- greater control at the mixer

- cheap to run with water heated by gas.

- a cheaper shower mixer valve can be used too.

- the existing system has no disruption except a cylinder change.

- no electrical work.

The only tap you need high pressure at is the shower. The cold wate feeding the cold tank in the loft usually runs up inside the airing cupboar meaning all the pipework is in the cupboard. I would avoid pumps.

indirect version. Use a normal high pressure thermostatic showe mixer. If the shower does not perform as well as you thought. Ramp up th cylinder temperature and install a DHW blending valve on the draw-off. Come with a pressure reducing valve. Take the cold off this valve too. Will giv a high pressure shower without any pumps and minimal disruption

-- Doctor Evil

[Doctor Evil]

" Ok. I know there are countless discussion topics on this (I've read them!) but I'm after a little confirmation before I go cutting int my pipework.

I am fitting a new shower to the bathroom with a separate pump. After much deliberation, I have run a dedicated 22mm cold feed from my CW cistern in the loft into my airing cupboard on the 1st floor. Th twin input pump is to be placed on the floor in the cupboard alongsid the HW tank. I now need to supply hot water from the HW tank.

Wishing to avoid a Essex / Wessex / Surrey or any fiddling wit flanges on the HW tank, I could T into the 22mm vertical pipe that is th vent and HW supply for the bath. This `should` be ok. However, it woul be infinitely easier for me to T into the horizontal coming from the HW tank that connects to the vent pipe / bath supply. If I brought a downwards pipe from this horizontal to the pump would all be ok or a I asking for trouble?

Kind regards

Alun

I take it the hot water tank has been plumbed with a combine expansion and draw off pipework scheme, by the way you describe it. If you ca take outlets from the hot outlet as low down to the floor as you can, the you won't have any problems of dragging air into your pump from th expansion pipe.

Looking at the pipework you have, you should be seeing a 22 mm Equa TEE with the branch pointing toward the top of the hot water cylinder right?

The straight through part of the TEE is pointing vertically straigh up and down, correct?

The pipework coming from the lower connection, toward the floor, i the supply to the water system for the rest of the house, is this right?

So, what you need is a plan to supply the pump with constant ho water, but you also need to keep the rest of the house supplied from the sam point, right?

If all the above have been answered with a "Yes", then you reall only need to place another 22 mm TEE fitting to the section of pipe that drops toward the floor. You will be better off keeping it as low to the floor a you possibly can, but the pump is only supplying one shower that i presumably very close to where the pump is sited. Let's say, within a couple of metres?

You're running the feed pipes for the shower head in 15 mm, for both, aren't you?

If this is also a "Yes" answer, then the 22 mm pipework for the twi pump will be well able to supply the shower without problems.

I don't understand why you had to run a separate 22 mm feed from th cold tank, when you could have drawn you cold supply for the pump off th same supply that feeds the hot water tank. "

Cold supplies to shower "must" have a dedicated supply. This ensure no scalding. Not to do so is irresponsible

-- Doctor Evil

[Ian_m]

SNIP

Just follow the instructions with the shower pump, for example

They are not done like this just to make it hard for you, they are done like this because it works.

I tried 22mm T in vent pipe as it was easy, especially using plastic push fit, cut pipe insert T connect to pump, job done except I ended up with a cavitating pump and basically an air/water shower. Fitted a flange and had a water shower.

Placing 28mm section in vent pipe will make no difference, the pump will pull the water from the easiest source which is the vent, you need a proper flange that does not allow the air in.

As for the person who said if you are running runs up into the loft and over to shower needing a vent valve to let trapper air out WHY ??? As soon as you turn the shower on the air gets pushed out immediatly.