UFH manifold flow/return pipe size

[crispy_wafer]

I've got about 12m to cover between my plant cupboard and my UFH manifold, so from knee height up to ceiling along the joists then down to knee height, a couple or 3 90 in the route.  UFH was designed to run in the region of 16 l/pm across all the legs, I was going to run this from the built in pump on the heat pump which should do about 20 L/min at 6m, but to be honest I really haven't got a clue about hydraulics.

 

So is it ok to run 22mm to the ufh manifold?

 

Thx

M

[JohnMo]

I would keep it simple, just run 28mm Hep2O, then without working anything out it will be fine. You also have to allow for the pressure drop through the UFH system as well. 

[crispy_wafer]

Thx, the outs on the current heat pump are 3/4" on to 22mm primaries, if i go up to 28mm then would that be an issue?  I’m thinking ahead a little, maybe in a few years if I have to swap out the h.p the replacement might need a bigger bore pipes.  The pipe work routing to the ufh manifold is going to be up in the ceiling so won’t be accessible without disruption in the future.

[JohnMo]

You don't mention heat pump size?

How long are the primary pipes to the diverter?

How far to your cylinder from diverter, what size pipes?

 

If you are starting a scratch install of a heat pump, you really need to doing at as low a pressure drop as possible.

 

22mm primary pipes - do you have a buffer?

 

You need to give us a lot more details.

[crispy_wafer]

Currently I have my 2nd hand ebay special 6kw Grant unit sat ready to go. has 3/4" outs on it.  So I've got 22mm from there, but I can go 3/4 to 28mm easily enough and repipe.  Pipe length 4m from h.p to the 3 port diverter at the cylinder then 12m to the manifold, no buffer, but the cylinder has one if we have volume issues... I've have a press tool, UFH capacity is in the region of 90-95 litres.  All the gear and no idea, me!  Just need to finesse my plans a little before I dive in!

 

The grant hp has an internal pump, the UFH manifold is a Wunda job, so came with mixer and separate pump, but from reading the latest threads these may want doing away with, the manifold doesn't have any actuators?

 

Grant HP internal pump flow rates below.

[JohnMo]

I would do 28mm from the 3/4 fittings, to a 28mm diverter. Drive the whole lot from the Grant pump without mixer or pump on the manifold.

 

You have loads of water volume. No actuators needed.

 

How are you controlling the Grant unit, per Grant or Chofu. Given an option I would go Chofu, every thing should be possible directly from the controller that Grant put in a cupboard.

[crispy_wafer]

I’ve read the grant installer guide and they make the install seem straightforward enough, and with the diagrams they have included even easier, albeit you need to use their wiring interfaces and dhw control relay and stuff.  I’ve read the Chofu install guide too and it explains everything and where the parameters are but i was struggling to put it all together as there is no schematic, it tells me where to cable the remote controller to, and what the other pins do, but the rest is hard work, for me!

[JohnMo]

16 minutes ago, crispy_wafer said:

I’ve read the Chofu install guide

Heat pump manuals for any make aren't easy, must read mine a hundred times. I will still read bits again.

[crispy_wafer]

Found a commissioning guide from a company in NZ, appears Chofu seem popular over there.  It shows simplified connections.  I'll wire up a thermostat but the plan was to set the HP to Weather comp and monitor how my building reacts.

 

Chofu-Commissioning-Guide.pdf