Combination tank shower.

[DaG]

Hi all.

is it possible to connect a shower to a combination cylinder?
I want to free up a cupboard which has my hot water cylinder in and also get rid of the cold water tank in the loft that feeds it. I'm thinking about putting a combinatation cylinder in the loft but I'm not sure about connecting the shower to it.
The current setup has the hot water drawn from the cylinder by a shower pump which also pulls cold water from the loft tank, giving equal pressures.
Will the combi tank be able to keep up with the shower pump? I'm guessing not as the little tank will be feeding the shower cold water as well as filling up the cylinder.
Can I connect the shower cold to the main water supply and just use the pump for the hot?
is there a way of altering the incoming mains pressure to equal what the pump pushes out?

Thanks, Dave.

 

[plumben]

Hi all.

is it possible to connect a shower to a combination cylinder?
I want to free up a cupboard which has my hot water cylinder in and also get rid of the cold water tank in the loft that feeds it. I'm thinking about putting a combinatation cylinder in the loft but I'm not sure about connecting the shower to it.
The current setup has the hot water drawn from the cylinder by a shower pump which also pulls cold water from the loft tank, giving equal pressures.
Will the combi tank be able to keep up with the shower pump? I'm guessing not as the little tank will be feeding the shower cold water as well as filling up the cylinder.
Can I connect the shower cold to the main water supply and just use the pump for the hot?
is there a way of altering the incoming mains pressure to equal what the pump pushes out?

Thanks, Dave.

No you can't pump a combination cylinder, there only really meant for flats IMO
And it wont provide enough water for the cylinder you'll suck it out with the pump faster than it will fill

 

[PhoenixServices]

If you have gas I would suggest seeing what the mains pressure and flow rate is and considering a combi. If it's one bathroom and just you or another person.

 

[Ray Stafford]

Will the combi tank be able to keep up with the shower pump? I'm guessing not as the little tank will be feeding the shower cold water as well as filling up the cylinder.

You are correct. It will not keep up, you will starve the pump of water, which will knacker it in short order.

Can I connect the shower cold to the main water supply and just use the pump for the hot?

There are a variety of bodges based around this concept - although don't let a twin impeller pump run with one chamber empty or closed. All the bodges are imperfect. Some creep up towards something approaching usability, but mostly not.

is there a way of altering the incoming mains pressure to equal what the pump pushes out?

Yes there is. Here But you are only gilding a bodge.

Do the job right.

 

[DaG]

You are correct. It will not keep up, you will starve the pump of water, which will knacker it in short order.



There are a variety of bodges based around this concept - although don't let a twin impeller pump run with one chamber empty or closed. All the bodges are imperfect. Some creep up towards something approaching usability, but mostly not.



Yes there is. Here But you are only gilding a bodge.

Do the job right.

Thanks for the replies everybody they are much appreciated.

Ray - what is the right way to do the job?

 

[DaG]

Hi again.

I gave up on the combi cylinder idea and have bought a new cylinder which my local B&Q were selling off for fifty quid.
My current cylinder is tiny about 400 x 800 including the domed top so it doesn't hold a great lot. It was ok for kitchen use and having a shower but a bath had to be a shallow one. The new cylinder is 450 x 1050 so should be better.

I've now obviously got to keep the cold water tank and I want to install the new cylinder in the loft to free up the cupboard the current cylinder is in. I'm going to move the tank and mount it on a platform in the highest part of the loft with the new cylinder alongside it.

My concern is that the cold tank won't be completely above the top of the cylinder. The bottom of the tank will be about 700mm above the loft floor so about 300mm of the cylinder will be above the bottom of the tank.

Will this affect the filling of the cylinder, or affect anything?
Also the current tank is a Merlin C25, not sure what it holds but as I'm intending to buy a new one I was wondering what the smallest tank I could safely use would be.

Thanks again, Dave.

 

[Chalked]

The tank bottom will need to be at least 600mm from the top of your cylinder. Even with that height, you will suck in air with the shower pump.

 

[Sparkgap]

Personally, I'd have gone for an unvented cylinder, assuming you've got half decent mains pressure all your problems would be solved!
My concern with having the tank so low compared to the cylinder is the hot water outlet off the top and the open vent as it sounds like they will be very close to the tank water level and if the level drops you will get air drawn into the system, more so if you've got a pump on it.

 

[DaG]

The tank bottom will need to be at least 600mm from the top of your cylinder. Even with that height, you will suck in air with the shower pump.

I can't get that kind of height for the tank. I thought (hoped) that with the cylinder filling from the bottom there would be enough weight of water to keep it all working. Ah well, another idea down the pan.

 

[DaG]

Personally, I'd have gone for an unvented cylinder, assuming you've got half decent mains pressure all your problems would be solved!
My concern with having the tank so low compared to the cylinder is the hot water outlet off the top and the open vent as it sounds like they will be very close to the tank water level and if the level drops you will get air drawn into the system, more so if you've got a pump on it.

I looked at unvented cylinders the other week but thought it looked a bit complicated compared to a vented system. Not to mention dangerous and expensive. I've had another look after reading your post and quite like the idea now.

I installed the current central heating system not long after moving into this house many years ago. It is controlled by a Honeywell Y plan with a floor standing gas boiler.

I served my time as a sheet metal worker and used to build caravan sized air con units. Pipe work, soldering and brazing was a part of the job and I have no problems doing plumbing work. However I know very little of the technical side of this work hence the questions I'm asking.

Would I be able to literally just swap my current cylinder for an unvented one? My loft already has mains water to fill the two tanks already up there and the pressure is very good. I can easily extend the flow and return pipes from the boiler into the loft and maybe use the current cylinders vent pipe for the hot water feed to the house.

I had a quick look on eBay and came across the cylinder below. It has twin coils, not sure what that means but would it be suitable for what I'm doing?

Do I need much else in the way of controls or valves for the cylinder or the rest of my current system? I'll do some reading up on this but would appreciate any opinion.

Thermsaver Solar 130ltr Indirect Stainless Steel Twin Coil Unvented Cylinder | eBay

 

[Chalked]

You will have to get a G3 qualified installert to fit this for you.
It will need registering with building control,benchmark commissioning form and guarantee registration. All these require a G3 installer.

 

[DaG]

You will have to get a G3 qualified installert to fit this for you.
It will need registering with building control,benchmark commissioning form and guarantee registration. All these require a G3 installer.

Yes I've been reading up on these cylinders and found out the need for a qualified installer. I'll see if I can get a price for the work and decide whether it's worth having done.
Thanks for every bodies help with this.

 

[stevetheplumber]

get lower height tanks to mount above the cylinder in the loft do the cold feed in 28mm and 28 out of the top of the cylinder 22mm vent and 22mm draw of

 

[DaG]

get lower height tanks to mount above the cylinder in the loft do the cold feed in 28mm and 28 out of the top of the cylinder 22mm vent and 22mm draw of

My cylinder us 114 litre /25 gallon. What do you think is the smallest tank I could use? I'd need to reduce the height of the tank a canny bit to get my cylinder fully under it.