Hot water secondary return

[smhstu]

Hi All,
Has anyone got a drawing of how a typical secondary hot water return system would be set out?
I think ive got it right but just wanted to check.
Its on a 300ltr megaflow with two boilers cascading for the CH but i want to pump the DHW at peak times

Cheers

 

[Dannypipe]

Generally you can rely on a 22mm flow and a 15mm return. There are comprehensive threads on this subject.

The fact that it's a 300 litre cylinder and two boilers indicates its a big system, so you may need some more advise to ensure it works correctly.

 

[smhstu]

Hi there
Ive got a 22mm flow and 15mm return right back to the cylinder, but wanted to confirm where i put the return leg into?
Does it go into the cold or back to the hot
My logic in thinking is if i loop to the hot with a pump its only gonna pump a loop of cold water round the system.

If i loop from the cold then there will be big heat losses in the pipework?
#
Just wanted a genral drawing just to compare,

Thanks

 

[NickH]

I could be wrong but the megaflow should/may have a dedicated connection for the return.

 

[SimonG]

Does the Megaflo not have a connection for the secondary return? I'm sure I've seen one!

 

[NickH]

Just looked on the Heatrae website and it shows they have a secondary return tapping, if yours is an old one it might be different.

 

[smhstu]

Sorry lads,
That woud be easy, theres no secondary return tapping, Thats what has got me thinking what would be the best option.
Dont want to seem like a novice, just want a bit of clarification.
The cylinder is a CL300.

 

[Reg Man]

Secondary return is a great idea, but very expensive to fit properly, and very expensive to run if not fitted properly. The entire hot water system must be lagged to a high spec, otherwise you will loose all of your hot water through heat transfer under the floor. A well fitted system will also make big saving in water wastage, depending on the length.

One of the big problems is, the thickness of the pipe lagging, with the pipe route which is available.

 

[smhstu]

Hi all,

its only going to be pumped at peak times to stop the lag of hot water.
So 6.00 to 6.30 and then 7.00 to 8.00
After then they will have to wait for the hot water. ( and probably run off a few litres of cold, but im all for trying to conserve water) ( cause im on a meter!!!)

Cheers

 

[SimonG]

The system fit megaflow shows the secondary return on the cold feed. Page 12 below.

http://www.tradeplumbing.co.uk/assets/images/heatrae_sadia/Megaflo_Brochure.pdf

 

[Dannypipe]

Yeah a cylinder that size should have a secondary return tapping. Normally just under half way up the cylinder.

Fitted two secondary returns on our last jobs. Cheaper cylinders than megaflows (Stelflow) and both had the tappings in 3/4 MI. So I'd be shocked if a Megaflow didn't.

Nothing shocks me that much though!

 

[Gray0689]

Tap in to cold feed to cylinder

 

[SPC]

I've fitted a couple of Megaflo's over the past few years and i'm pretty sure you link it back into the the cold main too the cylinder with a 22mm swept tee and the 22mm swept tee is normally a ba***rd too get hold of. Megaflo sell them seperately for this purpose. It seems wierd how they dont put a proper tap in for it though like they do on the range cylinders etc. hope you got it all correct.

 

[Reg Man]

Old school plumbing, the secondary return should be tapped in a 3rd way from the top of the hot water vessel.

 

[mark hurry]

I fitted twin megaflows in a large house a couple of years back with hw returns to cylinders. The return pipes tee in to the cold feed pipes between the expansion vessels and inlet to cylinder. But bare in mind you will need a bronze return pump,twice the cost of a normal one. Also you should have non tamper valves on the return pipe near to every appliance to balance the system.
Hope this helps.

 

[smhstu]

Spoke to Heatre and as SPC said its the swept tee.
Can only order one from them at £37.00!!!
Must be the reason they dont put a tap in.
Thanks for the replys guys.

 

[SPC]

£37 is a joke, we shopped around and i think we still paid in the region of £25 for it. but if thats what the instructions say, thats what we do!!

 

[tamz]

End feed
Trading Depot - End Feed Equal Swept Tee 22mm
Compression
KUTERLITE 657 22MM SWEEP TEE Pegler Yorkshire P-R BRANDS

 

[SPC]

that soldered one is a good find, alot more reasonable price than we found 🙂