Heatmiser UFH wiring centre with TS

[sphannaby]

Hi,

 

Just have a query about my wiring centre for my UFH.

Its a UFH2 by Heatmiser which now seems to be discontinued.  I've tried speaking with Heatmiser tech support but they were not much help at all.  The problem seems to be they can't understand the theory for how it should work with a thermal store.

Attached is the only literature I got with the UH2, there is no description of what the logic is within the board.

My guess so far has been that because I am using a TS which is temperature controlled with my system boiler I would not need to use any of the connections for the boiler enable, hot water valve or cylinder thermostat on the UH2.  The Heatmiser guy was insistent that I should use the hot water valve signal because I will need to trigger the external pump at my TS.

From what i remember Nick explaining to me with a TS I would not need an external pump as the TS pressure in conjunction with the UFH pump would be enough to draw through the water.  With that logic then my thermostats would simply enable the UFH pump and whichever zone is demanding heat.

Does this sound correct or will I be needing any extra signal?

 

Cheers

[Nickfromwales]

Yes, your spot on. 

The TS and the boiler 'talk' to each other via the cylinder stat and that heats the tank according to time / demand. 

The room thermostats talk to the actuators on the Ufh manifolds, and the call for heat from any room / zone ONLY needs to turn the pump on the respective manifold via the dedicated terminal in the Ufh control / wiring center ( UH2 ). 

There is no need for an external pump to circulate between the TS and the manifolds as long as the run isn't ridiculously adverse, eg 2 floors away at the other end of the building with 20 high points etc. These do pull through incredibly well all by themselves. 

Quote "The Heatmiser guy was insistent that I should use the hot water valve signal because I will need to trigger the external pump at my TS."

Did they mean trigger the manifold pump? Or do you already have that connected? Is this in and working, then failed, or are you installing all new from scratch?

[sphannaby]

No he didn't mean the manifold pump Nick he was talking about another pump to be located at the TS.  He stated you always need another pump from a cylinder as the manifold pump is not strong enough to pull through direct from a cylinder by itself.  I stated it was a thermal store rather than a cylinder and this blew his mind i think.

 

FYI, this is a new install going on at present.  Just wanted to make sure I have all my ducks in a row before the plasterers box in my last wiring route to my manifold.

[Nickfromwales]

I always chuck a spare 4 or 5 core in as a redundant cable when getting there later on will be tricky. 

Eg. I don't want to dig that back up

Whats the length of the run between the TS and the manifolds? I assume your running 22mm circs?

[sphannaby]

One manifold is 2 metres away the other one is 10 metres.  Yes both are 22mm flow/returns.

BTW, I have got some spares ran to pretty much all locations but I don't want to waste one of my spares before I have started.  Nice to know they'll still be spare until I find the next gadget I want to install.

[Nickfromwales]

The next gadget won't run on 1mm2 stranded flex .

Re the manifolds, you'll not need the additional circulation pump imo. 

Mom a previous job I trenched between the house and the garage ( much like the pic above of my current job ) and put a TS in the garage aka plant room. From there I ran a 15mm flow from the TS, around the garage, down into the trench, back up into the utility room, up the wall to the first floor joist space, along to the airing cupboard ( or "hot press" if your foreign ) and up to an Ufh manifold for the ( ground floor ) sunroom single zone / single circuit Ufh. The return was tee'd into the 28mm grouped return for the house radiators and job done. 

Thinking that the manifold pump would pull the heated water up there was my assumption. To my surprise, the manifold was warm, PRIOR to me fitting controls and energising the pump. The pipe work was all roasting hot and I was bemused as to how, only to then realise that there was a perfect convection loop flowing round like it was pumped! I had to install a 2port valve to STOP the flow for when the Ufh wasn't needed . That 15mm pipe run was over 18 maybe 20m long and up n down like a yo-yo. 

Point being, you'll be fine.

[Temp]

We have two Heatmiser wiring centres connected to a thermal store. Each wiring centre controls one UFH manifold (upstairs/downstairs). On our system the two BE signals on the wiring centres are OR'ed together and used to control a pump between the TS and the manifolds. The stats on the store control the boiler.

You may not need that pump between the TS and the manifolds - it depends on the manifolds. I questioned the need with Osma who provided our manifolds and they said it was required in our case.

 

[Nickfromwales]

Did they give a reason for including the additional circulation pump ?