Extending hot water circulating system

[xr4x4]

Have a hot water circulating system which supplies a new part of a extended old house that we are refurbing..gold pump type, via mega flow.

The hot water in the old part of the house was supplied via a vented tank and aga. These have been removed. The two parts are now connected via 22mm pipe to the mega Flow. Trouble is the hot water takes AGES to come through the taps in the old part of the house.

Now maybe we should of re run the pipe in 15mm, (22mm was already there) but due to the length of the run and wanting maximum flow, we where happy with 22.

I'm guessing the pump pumps water into the bottom of the tank out the top, then a hot pipe at the furthest point returns back to the other side of the pump?

Now question, can we T a new 15mm pipe run through a shorter route to tee in at the furthest point of the old house and then to the other side of the pump? Thus extending the circuit?

I can supply more info if needed.

Thanks.

 

[xr4x4]

BTW the system is working in the new extension.

 

[SDMCF]

I can't visualise how you intend the new layout to be. If you really mean to extend the layout so you end up with a single, longer, loop it should work without problems. If you will end up with 2 parallel loops one will probably be longer than the other and water might mainly or only circulate around the shorter one.
Also be aware that the pipework in the old part of the house may not be well insulated. It is surprising how much energy you lose through the loop if it is not well insulated. We have such a loop that isn't used very often because of the effect it has on our bills.

 

[xr4x4]

Well the only option I have is to add to, ie parallel.

Al I can see is the pump, with one end going to the water inlet of the tank and the other side of the pump/pipe disappearing into the floor, which is all hidden.

I think the system is a bit over kill in the new extension but vital in the old section of the house.

Will it working parallel? Or the possibility of disconnecting the existing loop and add a new?

The hot water pipes have been fairly well insulated and the pump is connected to a timer.

Thanks.

 

[SDMCF]

I think the only way to be sure is to try it. If it fails you could always change the loop to serve the old part of the house, or even add a second loop (& pump) for that.

 

[xr4x4]

Cool, Thanks.

Will talk to the boss.

 

[ajrobb]

I'd like to know where the bronze pump should be? I have an unvented tank with the return coming into the middle of the tank. My bronze pump is on the flow side. I'd have thought it would be better on the return with a check valve to prevent back flow. It's only duty is to keep water circulating slowly to prevent the pipes getting cold. Once a tap is open, I'd have thought the flow pressure would come only from the mains (or CWS for vented).

I agree that it is expensive to run if the old pipes aren't properly insulated, I lose heat from a 300 litre HWC in a few hours!

 

[SDMCF]

My tank is unvented and my pump is on the flow side also. I don't see any problem with having the pump there - in fact I think it is the best place. Consider what would happen when multiple taps were turned on at the same time. Could they take all available water supply, leaving the pump to run dry? Could the pump pull water past the taps, reducing flow at the taps? At least with the pump on the flow it is pushing water towards the taps. I can't see any good reason to put the pump on the return.

 

[picasso]

installing the pump on the flow is probably the worst place for it, air released from heating the water will find its way to the pump and shorten its life, it also puts a restriction in the pipe when there is no need for it, on unvented cylinders it should pump towards the cylinder on the return and vented cylinder should be facing away from the cylinder but still on the return.

 

[JohnD]

If you have a HW loop it is very important to insulate it very thoroughly, preferably using the BS grade of stiff foam lagging which is as thick as your arm

otherwise you have a very long thin radiator.

 

[SDMCF]

picasso, if the pump is on the return what do you think of the possibility that it could run dry when several taps are turned on? Isn't that a concern?

 

[picasso]

I suppose if the pump was fitted on a high point on the dhw pipework it might get starved of water but as they are normally fitted at the same level and close to the hot water cylinder I cant see the pump running dry.

 

[JohnD]

if it was on the flow, it would give an amount of improved pressure at the tap, surely a good thing on a tank fed system?

On the return it would have an amount of reduced presure, or even suction (not a good thing)

 

[ironman1]

if it was on the flow, it would give an amount of improved pressure at the tap, surely a good thing on a tank fed system?

On the return it would have an amount of reduced presure, or even suction (not a good thing)

Don't confuse a secondary circulator with a pump , two different things , as has already been said , bronze circulator should & always has been fitted on the secondary return back to the cylinder , this is the industry standard..................fitting before tap outlets can cause the circulator to cavitate along with reduced flow.

 

[ironman1]

on unvented cylinders it should pump towards the cylinder on the return and vented cylinder should be facing away from the cylinder but still on the return.

Is this a typo error Picasso?.................secondary pump whether installed on vented or unvented will always return water back into cylinder/calorifier.