Ive got a vaillant 637 boiler and vantage 150ltr water cylinder fitted. This is an unvented system.

The plumber has also fitted a bronze pump for circulating the domestic hot water around the house. Its a two bathroomed
house which has two thermostatic showers.

The plumber has advised that this pump can be wired in order to stay switched on all the time thus enabling hot water from the tap at demand.

However ive also been advised by a friend that this will cool the water in the storage tank making the system work uneconomically, as the boiler will have to reheat the water which has been cooling having left the cyclinder.

Can any wise person tell me the best way to wire this pump ?

Many Thanks. ??? ???

[quote author=greg  link=1107193861/0#1 date=1107198886]The pump should be wired so that it only circulates when needed - usually done by means of a time clock and a pipe stat [/quote]
But doesn't this mean that you've still got to wait for hot water at taps with a long leg of pipework to them?  I always thought 'circulating' hot water was always pumped continuously (perhaps off at night or other times when house is unoccupied).

I assume you recommend 'timed pump' in this situation as this is a domestic dwelling rather than a hotel or similar?

If the pipe runs are heavily lagged then the heat loss would be minimal (no worse than the water in the actual cylinder).  The beauty of this system is that you get 'instant' hot water from a hot tap which is miles away from the hot cylinder.

I have considered this system for my own house as we have a bathroom with a long run back to the cylinder. If the pump is controlled by a 'stat', how quickly would hot water appear at a distant tap?

Hi Greg, I get it now!  Sounds good.

Will 'gravity circulation'  take over when the pump is off?  In other words, doesn't the pump itself act as a barrier to the gravity circulation?

What current does a little bronze pump draw?  It can't cost much to keep it running continuously (just using a timer for main off periods) ?  This would then save the need for a stat?

Are my ideas rubbish    Just trying to get me head around what I can do here at JerryD towers  

Jerry,

Go to www.grundfos.co.uk and do a search for "comfort" then select product range from the search results - these are all bronse pumps, ideal for secondary returns, you'll notice that you can buy them as a basic pump or pump & timeclock or pump, timeclock stat
 
Hey PVC man - long time no see here  

Not been anything really interesting on here recently, spending a fair bit of time on DIYnot.com

I believe what you have is called a "secondary loop".

Usually found in hotels where the distance from hot water tank to tap is long.

It's not ususally intended to increase the water pressure just reduce the time it takes for the hot water to get to the tap. It's a nice feature to have.

Without the pump or with it off you have to wait longer for hot to come out and that wastes metered water.