Underfloor heating pack recommendation

[davphi338]

Hi,

Does anyone know of a suitable product that can be used for wet underfloor heating for an extension with a floor area apporx 24m2. Ideally I would like it to act as an add on radiator on my existing system. I have access to 22mm pipework under my bathroom floor that can be used for connection to the UFH system but cannot get access back to the boiler to run any new pipes. Ideally I also do not want to run any new electrical cables back to the boiler. I am still at the first fix stage of the extension so all other connections wouldn't be a problem. I will have other radiators in the extension, the UFH will promarily be used to provide comfort on the tiled floor.

Thanks for any advice.

 

[bengasman]

Forget it, you can not just add some pipe under the floor to the flow and return as an underfoor system. you need separate timer, thermostat, zonevalve, extra pump, manifold at a minimum.

 

[davphi338]

Yes, I understand that yoiu need an extra pump, manifold and thermostat. I was just hoping I could tap into the 22mm pipework to feed to the manifold. I only require a single zone so was hoping the pump would be controlled by some form of thermostat but the boiler would be controlled by my existing room stat. Thus everything would be kept local with no need to run anything back to the boiler.

I posted an earleir question regarding a pack that required a switched live back to the boiler and alos a dedicated flow/return which isn't really practicle in my situation.

 

[davphi338]

After a bit more research it looks like you can just lay some plastic pipe in your screed and then connect it to your existing heating system with a product like this http://www.uk-plumbing.com/danfoss-randall-fhvr-return-temperature-controller-p-1105.html

Unfortunatley for me its only for areas up to 10m2. So its back to the reasearch on heating packs.

 

[bengasman]

Practical or not, you will need a cable to your boiler for the zone valve, pump and timer, and a tee from the flow to feed the underfloor section independently.
The tee will have to be before the 2 zonevalves.

 

[davphi338]

Would something like this be suitable http://www.johnguest.com/part_spec.asp?s=UFHROOMPACK_S1 From what I understand you conect your flow/return to the manifold and this is then pumped around the UFH pipework. There is an external thermostat that controls the pump. It states that if the pump for the boiler is not running then there will be no supply of hot water to the UFH. Therefore I presume it is not absolutley necessary to have a connection back to the boiler.

The UFH is not going to be my primary heat source so I do not want anything overly complicated.

 

[bengasman]

Forget it, can't be done other than above.

 

[davphi338]

bengasman, do you have any experience of Vaillant boilers. One of the other reasons that I don't want a connection back to the boiler other than having to try and get a cable back their is that the boiler is currently operated from a Vaillant RF360 programmable room thermostat and I am unsure if I would be able to still utilise this if i have to connect another external timer/thermostat that controls the UFH.

Any advice much appreciated

 

[bengasman]

UFH will run totally separate; wiring wise, it hooks up like cylinder. I wouldn't recommend it as a diy job if you are not savvy with heating.

 

[David937]

Not sure if this is relevant but I don't think Vaillant controls are compatible with non Vaillant controls, so if the Vaillant controller turns the boiler off then any call for heat from third party controllers will be ignored.

 

[bengasman]

Don't know the details about their controls, the vaillant service is so bad that I have no intention ever installing one.
No doubt some of the vailant experts will be able to tell you in detail.
Might be an idea to post a separate thread regarding v. controls compatibility.

 

[davphi338]

Looks like I will have to contact Vaillant technical department. They do a control box that is used to connect to a 2 port valve arrangement.
http://www.vaillant.co.uk/installer...nostics/Controls/produkt_vaillant/vrt-65.html

This may be the way forward.

 

[bengasman]

Make sure you have a cuppa ready and the paper in front of you.
Half an hour to an hour on hold is not unheard of. And it is a premium number, so it will cost you a few bob.
Can't remember if they ask for "corgi"number, some do, some don't.
They are also quite good at giving political answers if the hard truth does not sound to good.
I would try the forum if I were you, pretty honest, pretty good, and totally free.

 

[Norcon]

Hi,

Ideally I would like it to act as an add on radiator on my existing system. I have access to 22mm pipework under my bathroom floor that can be used for connection to the UFH system but cannot get access back to the boiler to run any new pipes.

If its a diy job then just connect off these pipes but use a tmv, pump and a small manifold for the job. Not "small area (ripoff) packs" for the unwary.
It will operate like the FHV-R as regards control. ie no separate zone valves and will shut down when the normal heating shuts down and if you are happy with this then its the way to go IMO. Run it at 50c and make sure ceramic tiles or similar are laid.
Pipe spacing 150mm max (100mm if you can afford it as this will increase the response time) and 70mm high density insulation beneath and use a fibre reinforced screed 50mm in depth.
Oh and the FHV-R covers 15 sq meters with 15mm pipe.
BS EN 1264 states 159 W/m@150mm spacing@50c for ceramic tiles in 75mm screed with 50mm above pipe@20c design room temp increasing to 185W/m@100mm spacing.