Underfloor heating help required

[hbooth]

Hi all,

 

I'm currently in the process of a new build and I have put plumbing the underfloor heating in on myself however I've never done it before so have loads of questions.

 

The pipework for the ground floor underfloor is in and the screed has been poured. I have to hook up the manifold and run all cables for thermostats etc. Its will be run from a Diakin heat pump. The guys putting the heat pump in said for maximum efficiency to have the whole downstairs which is 9 loops as one temperature zone. So the first question is what else do I need to have in place to make this work? I assume a single zone valve going into the manifold will do the trick bit I have no clue how to wire that up to the heat pump and the thermostat.

 

Next question, is only having one heat zone actually the best way to maximize efficiency? Or will that actually end up costing me a fortune in electricity costs to run?

 

Next question, if I only have one zone will there be an easy way to switch some loops off if needed? I just think that some of the loops that are in small rooms will end up getting too hot if the doors are closed etc. I guess an isolation valve in the loop would do the trick if there's no better way.

 

I will be laying all the first floor pipe work and Installing the manifolds, thermostat etc. Myself. Will it be best to have the upstairs on separate heat zones or will one big zone also do the trick upstairs? Or is this really just a case of personal preference? If I only have one big zone how does that tie in with the heat pump? I would assume it can be the case that if either the downstairs or the upstairs call for heat it will make the heat pump kick in?

 

I know this post is a bit all over the place but I'm really still getting upto speed with the heating so thanks in advance for any help/advice.

[Pocster]

What controller arrangement do you have for the thermostats ?

You could have actuators per loop controlled by this . Then you can control each individually or if you wish have all on or all off I.e as though just 1 big zone .

[hbooth]

5 minutes ago, pocster said:

What controller arrangement do you have for the thermostats ?

You could have actuators per loop controlled by this . Then you can control each individually or if you wish have all on or all off I.e as though just 1 big zone .

I don't have any controller arrangement as yet. I'm trying to establish what's going to be best, most cost effective and something that I can possibly do myself. My heat pump engineer suggested one big zone for downstairs which would save on the cost of all the actuators and wiring hub etc. 

 

He suggested one thermostat centrally located, which I should think will work fine. We currently rent and have oil fired central heating and there only one thermostat downstairs which we seem to manage ok with. I just wonder if it will be the same with an ashp and if yes then I need to figure out how to wire it all up. If no the I need to figure out how to wire up all the actuators and thermostats etc. Like I said I'm really new to this so trying to figure out the best route to take and then figure out how everything is installed.

[ProDave]

Single zone or individual room thermostats is a bit of a marmite question, very much a personal preferance.  It also depends on what level of build insulation and air tightness you are aiming for.  Many on here build passive houses or very close to that, that require very little heating and a single zone works well with that and most find with such a well insulated house there is no need for heating upstairs.  but if you are just building to basic building regs values you may well find individual room control is better.

 

To give you some idea of what we are talking about, this is a picture of my little upstairs manifold, just 2 loops for the 2 bathroom floors.  A more typical larger manifold is just longer and has more pipe loops and actuators.

 

 

A proper manifold should have a circulating pump, and temperature blending valve and then the manifold rails in this case with the actuators on the bottom and flow meters on the top rail.  the grey box underneath is the controller, a cheap generic no name one from ebay.

 

If you choose to go single zone you don't need the grey box (under £100) and you don't need the actuators on the bottom rail (about £15 each)

 

If you go single zone it is much more important so spend time balancing the flow between the loops by adjusting the flow meters, so that each room heats up at the same rate.

[JohnMo]

Single zone means you don't need any room thermostats, we had then then removed them.

 

You set different room temps you balance the flows, more flow means more heat, less flow less heat.

 

I take it will run the manifold without mixer and pump direct from ASHP?

 

How it's being suggested is exactly how I run my gas boiler, and soon to be commissioned ASHP.

[Nickfromwales]

3 hours ago, JohnMo said:

Single zone means you don't need any room thermostats, we had then then removed them.

 

You set different room temps you balance the flows, more flow means more heat, less flow less heat.

 

I take it will run the manifold without mixer and pump direct from ASHP?

 

How it's being suggested is exactly how I run my gas boiler, and soon to be commissioned ASHP.

Shouldn't we ask about the fabric / standard of the build before suggesting no stats per room?

 

@hbooth

Who designed the UFH and what calcs have been done?

1st floor should 100% have stats per room.

 

4 hours ago, hbooth said:

We currently rent and have oil fired central heating and there only one thermostat downstairs which we seem to manage ok with.

To rads or UFH? If rads, then you'll have TRV's on each rad to give individual room temp control.

[hbooth]

Hi, thanks for all the replies.

 

The build is to fairly basic building regs. Brick and block, 100mm Cavity full fill insulation. The loft is a warm roof insulated with 140mm Actis Hybris and then a layer lf HControl to get to a U-value of 0.15. The Ceilings will be insualted with 100mm acoustic roll, along with all stud work walls. I'm hoping this is then fairly well insulated.

 

I think for downstairs a single zone makes sense for our needs. So I just need to figure out the way to set this up. (any help on this would be appreciated)

My though is a single 28mm zone valve feeding the manifiold, that is activated from the single thermostat downstairs? Will that work? If someone can give me an idea of how this will work/should be wired up that would be great. Or if I'm way off with my thinking advice on the best way to achive this would be great.

 

 

I think for upstairs we'll go with different temerature zones, so I'll need actuators and thermostats. We have 4 bedrooms, 2 en-suites, 1 family bathroom & the hall/landing(I probably wont bother heating this as it will have pipe to each room and heat rising up the stairs). So I think 7 different tempearature zones will do the job. So that will be 7 thermostats to 7+ actuators depending on how many loops each zone requires. So my questions are:

• What size cable shoud run from the thermostats to the actuators?
• How do I wire up the actuators to the wiring centre?
• What size cable do I need to supply the wiring centre?
• Does the wiring centre need to connect to the ASHP?
• The manifold will have a pump, does this connect to the wiring centre? Does it just need a mains supply?

 

Really sorry I have so many questions as I am a complete newbie to this. If anyone has any websites/youtube videos etc they recommend me checking out that would be much appreciated.

 

Thanks again for all the replies so far, It really is much appeciated.

 

[Temp]

For a single zone set up you have one stat connected to all of the actuators on the UFH manifold.

 

If some rooms overheat you can potentially adjust the flow to those rooms (balancing).

 

You could also consider running the wires to allow extra room stats to be added later.

 

1mm^2 or 1.5mm^2 wire is normally fine for the stats. There should be instructions with the wiring centre but note some are designed for 12V stats and others 230V. Some fancy systems can also transmit data to/from the stat and might need an extra core in the wire or use CAT 7 cable instead. If in a rush I would install 3 core and earth mains cable as that can cope with most basic stats/programmable.

 

 

[Temp]

The wiring centre controls the manifold pump.

 

The wiring centre also controls the ashp unless you also have a thermal store.

 

 

[HughF]

Look in the daikin installation manual and wire/plumb it up as per their designs, using their controls.

 

that way you’ll get best efficiency.

 

Im going to get shot for saying this here, but no need for the tmv or pump on the ufh manifold, let the ashp do it all.