Which pump to boost hot water ?

[wwwebber]

Hi, will be having a new shower installed soon which will use a thermostatic mixer where the hot water will come from the hot water cylinder in the same room. It needs a boost so we've asked for a pump to be installed on the hot water feed.

We also intend for the electric shower to be replaced with a mixer at some point in the future so need a pump to cater for both. Apparently its easiest if we install a pump to boost hot water throughout the entire house which I'm fine with.

Which pump do I need though ? - there's so many to choose from. Any advice would be very much appreciated. Thanks.

 

[wwwebber]

I'm assuming that I need something called a Domestic Home Booster ?. The link below looks like something I might need but not sure if its good enough for two showers etc ??

http://www.onlinepumpsupplies.com/grundfos-upa15-90n-domestic-circulator-240v

 

[wwwebber]

Some more info, my system is positive head gravity system

 

[terryplumb]

Thermostatic shower mixers require balanced hot and cold water pressures. On gravity fed system ,you would take a dedicated cold supply to the pump from the loft tank ,and the hot from the cylinder ,via a special flange ,to the pump. Pump would then deliver both to the shower mixer. You really need to consult with your plumber ,as there are other considerations to take into account with what you are thinking of doing. Is the cold water storage tank large enough to support supply to two simultaneously running pumped showers , is mains pressure and flow adequate to replenish the cold water storage tank when pumps running.

 

[wwwebber]

Thanks @terryplumb. Everything is currently mains fed in the house except for the hot water cylinder which is fed from the cold water storage tank. Its an old property. Is this a problem ?

 

[terryplumb]

A problem ? Regarding what specifically , besides above mentioned?

 

[wwwebber]

deleted

 

[wwwebber]

Does a twin shower pump balance the hot and cold output pressure then to suit thermostatic mixer showers ?

Apologies if I'm getting this wrapped around my head.

 

[terryplumb]

Ha Ha , welcome to the world of plumbing mate. Single Impellor boosts only one supply. Twin boosts hot and cold. Regenerative bit noisier than impellor type ,but bit cheaper. As thermostatic mixers need balanced hot and cold pressures its best to have the pump supplied from both gravity hot and cold. I have seen mixers installed with just hot pumped and cold direct from mains and nowt but grief as they were at different pressures. The mains pressure of any property is subject to fluctuation at any given time of supply demand .

 

[wwwebber]

Righto, this is gonna be a bigger job then. So in conclusion I need a new supply from the cold tank to feed the shower alongside the cylinder fed hot water to equalise the pressure. Will have to think some more on this - thank you.

 

[picasso]

If your going to spend money on running new supplies to a thermostatic shower it might be worth looking at an unvented cylinder, cant see there being a huge difference in cost.

 

[Madrab]

1st things first ... you need a proper survey of you mains and gravity systems and get a professional that is experienced in advanced hot water systems to suggest the best option, as there are a couple of different ways you could go.

If you are going to have more than one shower on a whole house pumped system then you also need to consider any pressure or flow drops when more than one outlet is being used and design the system accordingly.

The only way a pump will be ideal and not affected by anything else is to restrict the dedicated pumped feeds only to the showers

 

[wwwebber]

Thanks for the replies folks. Gonna keep it as simple as possible at the moment. The existing shower in the bathroom is an electric one (really pathetic) which will remain so for a year or two yet, the priority is to get a new decent one up and running in the en suite where the hot cylinder is and where the cold water tank lives above. When we can afford to do the bathroom in the future and hopefully replace the electric one with a another mixer shower then we'll look at the various options and additional costs to get everything sweet. For the moment we'll stick with a pump and a new cold feed to drive the new mixer which will make the old shower redundent - ie they wont be used at the same time.

Plumber now booked to start things off. Thanks again.