Polished concrete and UFH

[vala]

We have a polished concrete floor being installed in July so next month have to install the UFH.

Had a design completed with Wunda and they have omitted any pipes under the kitchen units/fridge freezer etc.

 

As it's a polished concrete floor, and expecting to be running low flow temps would having it under the units, fridge freezer have as much of an adverse effect on those appliances?

My thoughts were that the heat would end up underneath them anyway as it's all being poured as one slab.

 

So just wanted to gain and advice from here as to whether I'm on the right track and have the UFH everywhere?

For what it's worth the fridge freezer will be a free standing unit.

[JohnMo]

Just now, vala said:

polished concrete floor

Polished concrete or tiles are no different. In open space your floor temperature will around 2 to 6 degs above room temperature. Air trapped beneath kitchen units is going to warmer that the room.

 

Make your own call.

 

I didn't have any UFH pipes below beds, wardrobes, any kitchen units. Does house feel cold - no, even at 300mm pipe centres I don't flow high temps.

 

You will get answers that say do and others like mine that say don't. You need to consider your house layout and likelihood of being changed in the future. For example - Our house is not likely to be reconfigured, as it's all geared to views, other/yours houses are different.

[nod]

Most companies will ask you to mark the units islands etc I think the cupboard's would get quite warm 

Weve 150 centres in our current build and 300s in our previous build 

There’s really no noticeable difference 

 

[Gus Potter]

1 hour ago, nod said:

Most companies will ask you to mark the units islands etc I think the cupboard's would get quite warm 

Weve 150 centres in our current build and 300s in our previous build 

There’s really no noticeable difference 

Philistine here.. Nod makes a good point.

 

I've run my UF pipes under my island units. The cupboards are warm... keeps the pasta dry for example. I have a gap at the top of the plinth to let excessive heat out.

 

Where I have my fridge and freezer I opened up the pipe spacing.. just to provide a bit of residual heat.

 

I've been doing this for decades. UF is a pragmatic art.. the focus is on the art!

 

What I do is have plenty loops, and short flow adjustable loops. Commercial companies will try and be smart and seek some cost advantage.. which is bonkers when you think that UF should at least last the lifetime of the house.

 

 

[Gus Potter]

To add a bit.. of a rant!

 

My day job requires me to use some complex software. But if you put rubbish in you get rubbish out. With modern software you need to construst a model, could be an SE model or UFH model.

 

I've learnt that in UFH design you can get a feel for how much heat you need to put in but most importantly you need to know where to apply the heat. A badly thought out UF design can be disappointing to say the least.

 

I'm going to go back to some old sckool stuff to demonstrate a point. Say in the 1980's when folk were able to afford gas central heating. There were two basic schools of thought.. do you put the radiators under the windows.. where the cold comes in or do you put them at the entrances to the rooms where you are less likely to put furniture? Now the cheapest option was to keep the rads at the doors. But you set up big convection air currents in the room. The same applies to UFH. Think about where you need the heat.

 

We often have big areas of glass and open plan spaces.. that is where you need the heat.. where the glass is, I reduce my UF pipe spacings in these locations. This is where part of the art comes in.. in fact it's just common sense. Say you have a door then you want the floor there to be hotter so it gets rid of any moisture that may be coming in from your shoes. It's design touches like this that make UF work well.

 

Loop cad etc will get you so far but to get the best out of UF requires you to trust your common sense..

 

 

Edited May 12 by Gus Potter

[nod]

47 minutes ago, Gus Potter said:

Philistine here.. Nod makes a good point.

 

I've run my UF pipes under my island units. The cupboards are warm... keeps the pasta dry for example. I have a gap at the top of the plinth to let excessive heat out.

 

Where I have my fridge and freezer I opened up the pipe spacing.. just to provide a bit of residual heat.

 

I've been doing this for decades. UF is a pragmatic art.. the focus is on the art!

 

What I do is have plenty loops, and short flow adjustable loops. Commercial companies will try and be smart and seek some cost advantage.. which is bonkers when you think that UF should at least last the lifetime of the house.

 

 

If you’ve no food stuffs in the cupboards Or fridges I don’t suppose it matters 

[Gus Potter]

8 minutes ago, nod said:

If you’ve no food stuffs in the cupboards Or fridges I don’t suppose it matters 

And here you are demonstrating common sense! I know @nodyou have a vast amount of experience and I think we are of like mind. Ok.. I hear you maybe saying .. on the odd occasion I might concur with Gus.

 

So long as you at least make it it bit future proof then spot on. 

 

OK folks: In my mind future proofing UFH is; no fancy controls, no apps and shite, basic plumbing components that your local plumber can buy off the shelf. I'm an SE (reinvented builder) and primarily we design with no bollocks! Things need to last!

 

If you think about it.. UFH is just a large radiator on the floor. But by applying common sense you can heat different parts of it by having loops.. and then fine tune it where the cold comes in..and where the floor gets wet.. this is improtant to dry out the mats at the door so you don't stain your oak flooring say or soften the varnished / oil finish. In my own house.. it's a bit eclectic we have rugs and stuff on the floor, my wife is a bit of an interior designer.. it totally stuffs any loop cad things and the U.. value calcs. We have some furniture.. big sofas.. they trap the heat.

 

Now when you take all that account any heat loss model is just an estimate.

 

When I first started out on the UF malarky some 30+ years ago ( folks.. I've not always got it perfect by the way.. have learnt from my mistakes) we struggled to get it to emit enough heat as the U values of the walls, roof and glazing where much higher. But now the regs make UFH much more viable. But the same basic rules still apply.

 

For all on BH that are thinking about UFH.. go for it..trust your common sense..  it does not cost that much more but.. the luxury is.. from my experience.. well worth it. Even my old Mum at 94 does not have to bring her slippers!

 

 

 

 

[Nickfromwales]

Where I meet the run of kitchen units I stop the pipes at 450-500mm away from the walls, but where there is an island or peninsula I just always go under them. The temp is so low it really doesn't do any harm at all, and unless you plan on keeping perishables in those particular units it matters not afaic.

[Gus Potter]

2 minutes ago, Nickfromwales said:

Where I meet the run of kitchen units I stop the pipes at 450-500mm away from the walls, but where there is an island or peninsula I just always go under them. The temp is so low it really doesn't do any harm at all, and unless you plan on keeping perishables in those particular units it matters not afaic

OK @Nickfromwales let's not split hairs here.

 

You recognise that we need to at least have some residual heating under the units.. that is so common sense! 

 

Folks. @Nickfromwales does this as a day job.. listen to what he says. I've also been dabbling in this UF malarky for 30+ years. I agree with Nick.  Nick says ( i think in the spirit of the discussion).. essencially reduce by half the spacing under where you are confident your units are going to go. That is what In would do.. it is so simple! It stops damp problems and just acts as a bit of a stop gap, provides a bit of redundancy when in 10-15 years time the system stops working so well.

 

 

 

 

 

 

 

 

 

 

[BotusBuild]

As I know where my units are going I am not running pipes under them. In the islands we will have an extractor unit for the hob and that will no doubt create heat under the island. So, shrug, WTF.

Low flow temps , it'll likely make no difference if you run pipe or don't 

[Nickfromwales]

35 minutes ago, Gus Potter said:

OK @Nickfromwales let's not split hairs here.

I wish to stay up and fight 🤺 lol.

 

36 minutes ago, Gus Potter said:

I've also been dabbling in this UF malarky for 30+ years

Same here, and seen it done badly sooooooooo many times by others that I am happy to consider myself an "expert", or at least someone who does these jobs and gets zero complaints!

1 minute ago, BotusBuild said:

Low flow temps , it'll likely make no difference if you run pipe or don't 

Yup. I just do the islands and peninsulas as I work for clients; these folks change their minds a LOT btw, so I install some insurance (aka protect them from themselves).

[Barnboy]

I was once told to put ufh pipes everywhere to allow for future redesign and then lay off cuts of kingspan under the kitchen units to stop the heat rising up into the cupboards.

[BotusBuild]

7 hours ago, Nickfromwales said:

install some insurance (aka protect them from themselves).

😂

[vala]

Thanks all for the comments.

Looks like some of the base units in the kitchen area will contain food, but as I don't know which ones yet think I'll play it safe and just leave that area unheated.

Got the final plans through from Wunda and aside from a phantom door (circled in green) which isn't in our house, they've put the pipe everywhere in the small room at the front.

Here there's just a washing machine and small unit for a wash basin.

Worth veering round those 2 or just go under?

 

[JohnMo]

I must be missing something - UFH in garage?

[vala]

1 hour ago, JohnMo said:

I must be missing something - UFH in garage?

yes.

thought it best in case that ever changed at some point to a habitable room.

Plus I often work in there, so saves me firing up a heater.

[JohnMo]

12 minutes ago, vala said:

yes.

thought it best in case that ever changed at some point to a habitable room.

Plus I often work in there, so saves me firing up a heater.

So will the garage floor be insulated as well as the rest of the house? If not you will be unlikely to get a balance out of the heating and most of the heat in the garage will take the easiest route - which is down, not into the room.

 

Make sure you really think this through.

Edited Thursday at 20:41 by JohnMo

[vala]

5 minutes ago, JohnMo said:

So will the garage floor be insulated as well as the rest of the house? If not you will be unlikely to get a balance out of the heating and most of the heat in the garage will take the easiest route - which is down, not into the room.

 

Make sure you really think this through.

exact same level of insulation and floor build up/finish as the rest of the house. It's all getting done at the same time.

[Mike]

4 hours ago, vala said:

Looks like some of the base units in the kitchen area will contain food, but as I don't know which ones yet think I'll play it safe and just leave that area unheated

There is no significant benefit from omitting heating under the cupboards. The floor beneath will heat up anyway (it's in contact with the rest of the floor) and the cupboards will heat up too (they're in contact with the rest of the room). Omitting the pipe just means that it may take them an extra hour or three to reach a stable temperature. Just put any temperature-sensitive foods in the fridge.

 

Edited Thursday at 22:47 by Mike

[Nick Laslett]

Lots of excellent posts in this thread. For me the cooling aspect of UFH, in concrete with ASHP was actually more interesting. It didn’t seem to get as much commentary. Maybe, the considerations for UFH cooling are basically the same as heating? There is the dew point issue. 
 

I put more UFH in my upstairs concrete floor than I did downstairs, purely for the extra cooling. I was always going to have a poured concrete first floor, so being able to use it for cooling was another positive. 
 

Like a lot of my buildings choices, this might be a foolish solution for cooling a house. 

 

A note about Air conditioning. I spent 12 years living in the Middle East, with A/C running 24/7. Even if you only need A/C for 2-4 weeks a year in the south of England, I was really keen to avoid having to install it.

 

[JohnMo]

3 minutes ago, Nick Laslett said:

There is the dew point issue. 

Which is not real if you set up the system correctly. I manage the floor temp at around 19. This means the heat pump supply flow goes down to around 11.8. neither are an issue.

 

8 minutes ago, Nick Laslett said:

note about Air conditioning. I spent 12 years living in the Middle East, with A/C running 24/7. Even if you only need A/C for 2-4 weeks a year in the south of England, I was really keen to avoid having to install

I have the same feelings for it also. Not a fan!

[jack]

12 hours ago, vala said:

exact same level of insulation and floor build up/finish as the rest of the house. It's all getting done at the same time.

 

We use our garage as a gym. It has the same 300 mm of insulation under the slab as the rest of the house, and is insulated to slightly better than building regs standard. The main thermal weaknesses are airtightness (garage door and rear access door) and the garage door itself (insulated, but obviously not as much as a decent door, let alone a wall).

 

We hemmed and hawed about adding UFH and wish we had now. It's bloody freezing using it on cold winter mornings! I'd only have run it intermittently during the coldest weather to keep the floor temperature a few degrees higher than it gets now, so it really wouldn't have used much energy.

 

1 hour ago, Nick Laslett said:

Like a lot of my buildings choices, this might be a foolish solution for cooling a house. 

  

Absolutely not! We have polished concrete floors downstairs and they keep things very comfortable with the underfloor cooling on during runs of hot weather (all covered by excess solar).

 

I really wish we'd done the same upstairs. If doing it again, I'd probably have tile with UFH upstairs. Use rugs during winter to keep feet off tiles, and remove the rugs in summer so the underfloor cooling can do its thing.