Retrofitting underfloor heating - Good or bad move?

[DaveApp]

Hi. (First post, so go easy on me ).

We live in a 1930's terraced house and are planning to do some major renovations to our downstairs in the spring. I've had at the back of my mind installing wet UFH for some time (leaving the radiators upstairs), but have a few complications that I'd like some advice on.

As usual with this period of house, we have a floating wooden floor in the main part of the building, we also have a concrete slab floor out in our rear extension which houses the kitchen.

We're looking to knock down all walls necessary to create a fully open plan kitchen/diner between what would have been the back room of the house and the kitchen/extension (That'll be the old back wall of the house and around 6ft of the wall going back in to the house which would have separated the old kitchen and the dining room before the extension was made - I hope that made sense!).

Because of this and other things that we want done, we're going to move and replace our old boiler with a Combi (one of these if anyone have any comments on it?). The floor is going to have to come up because we need the place rewired, chimney breast removed and a radiator re-positioned because of the removal of one of the walls - That is of course if we keep the radiator.

So because of all this work, I'm wondering whether it would be best to decommission the radiators downstairs and retrofit UFH. I've been looking at two systems from NuHeat and PolyPipe, which on the face of it look like they'd fit the bill. However, call me a cynic, but I'd rather go on experience rather than sales information!

So here comes the questions...

1. These new retrofit systems have very low build up requirements and so must have very good insulation underneath them to match that of traditional systems. However, I've read that a BCO would not look on these systems particularly favorably because of the insulation. Does anyone have any experience on this?
   
   
2. Would there be any issues spanning UFH between a floating wooden floor and a concrete slap. I'm wondering about expansion differences etc?
   
   
3. If the marketing material is to be believed, it sounds as if these systems can provide a full replacement for radiators on our ground floor. I'd love to hear your experience.
   
   
4. Price - Considering the amount of re-piping needed to move the boiler and ground floor radiators, would I be right in thinking that pulling the old downstairs system out and putting UFH in instead, there would not be a huge difference in price? And considering we'd be talking about 45m², if anyone could throw a ball park figure, that would be really useful.
   
   
5. Floor covering. We're looking to putting either laminate wooden floor over the top or posh vinyl. Any preference with regards to heat transfer?

Any other experience would be extremely useful. I haven't asked anyone in for quotes yet, but when I do, I'd like to have a good idea of what I'm talking about.

Thanks in advance of any responses,
Dave.

 

[muggles]

Morning
I'm a NuHeat trained and approved installer so I'll admit some bias towards their systems, but having said that they are very good

Your plan sounds sensible in principle and I'd recommend LoPro Max. For the bits with the wooden floor, consider taking the floor up and putting insualtion between the joists. This will improve efficiency and reduce running costs. The concrete side should be fine as-is.

UFH is invariably more expensive to install than radiators, but cheaper to run. NuHeat will guarantee that it provides sufficient output to heat your room. You're probably looking at around £600 to buy the kit and £1200 to fit (ish).

Personally wouldn't touch your boiler choice with a bargepole, or anything from that manufacturer. I'd choose this or this

As for floor covering, choose it before you order the UFH and NuHeat will design the system to make sure it works

 

[Agile]

I can see no reason to expect UFH to be cheaper to run.

You are providing heat to make up the heat loss of the property and that's the same whatever heat emitter you use.

If you add insulation between joists then that will reduce heat loss regardless of the emitters.

You say a lot but don't say if the walls are solid.

Please read up about the longer warm up time of UFH.

There is a lot of "building" cost involved in adding UFH to an existing suspended floor and solid floor. I would have suggested a higher installation cost.

My preference would always be for radiators in that kind of house IF you all go out to work during the day. UFH is better when the house is occupied all day by home workers or retired people.

Tony

 

[muggles]

@Agile UFH works at a lower flow temperature. You know that it's cheaper to run boilers at 65° than 85°...same principle with a 45° UFH flow temp. Also, you're heating the things lower down first, rather than relying on convection to overcome losses through the ceiling and eventually circulate heat back down from above.

As for the "building" cost involved, and your comments on cost generally, I have to ask how familiar you are with the installation procedure for LoPro Max? How many LoPro Max systems have you actually installed yourself?

 

[DaveApp]

Thanks for the responses so far, they've been helpful.

I am aware of the build costs, but considering the work that will be done regardless of the heating, I saw this as an opportunity that should be at least considered.

I have read about UFH and changed my mind more times than I can remember and it's these low-profile retro fit systems that make it an option - I certainly wouldn't consider it if i had to lay a thick screed slab.

The house is used throughout the day as I regularly work from home so that ticks that box. Again, as far as warm up times are concerned, I am under the impression that retro fit systems are more responsive (due to the fact that they don't have to warm up a thick slab first), but will still be slower than radiators and loose their heat quicker than traditional UFH.

Insulation between joists sounds like sound advice and something that should be easy to do considering work that we're planning. Our walls will be the brick side walls of our house.

@muggles, why would you not go close to the boiler? I've always thought that Worcester were well recommended! And why would you favor Intergas instead?

Thanks again for the responses, it's great to learn from you points of view and experience.

Dave.

 

[muggles]

Which magazine like Worcester, as do builders and simond on here. The Compact is apparently a bit difficult to install without sharp edges cutting your hands, and everything is so squashed together inside the case that it's more difficult to work on than is strictly necessary. It's a bit plasticky in places too.

Intergas are much simpler boilers - only four moving parts in the combi and no diverter valve (a regular failure part in other combi boilers) - all water and gas ways are brass and copper, you don't have to use the manufacturers own expensive controls to get maximum efficiency out of them, they're much easier to maintain with all parts being easily accessible, and they have proven reliability whereas the Compact is fairly new to the market

 

[Agile]

UFH works at a lower flow temperature. You know that it's cheaper to run boilers at 65° than 85°...same principle with a 45° UFH flow temp. Also, you're heating the things lower down first, rather than relying on convection to overcome losses through the ceiling and eventually circulate heat back down from above.

We still don't know what kind of boiler he has. Reduced flow temps opnly give a bit of saving with a condensing boiler.

However in this case he is keeping rads upstairs. So he will need a set boiler flow temp of 75 C to supply those and then have a separate pump and mixing valve to reduce the flow to about 45 C. So little reduction in the efficiency of the boiler even if it was condensing.

As far as building costs are involved, the floor could just be insulated without having to take it all up in most cases or without taking any up if there is adequate crawl space underneath.

To fit UFH it will be necessary to take up all the floor covering if fitting an under board system and most builders will then prefer to recover with chipboard ( Ugg ) rather than have all the work of refitting the boards.

If he had adequate ceiling and door height then he could have an above floor system as you suggest and I agree that the cost of doing that is about £1200 labour excluding any under floor insulation although to me not fitting that would be very penny pinching.

After all this discussion I am probably going to be prompted to insulate under my smaller front room this Christmas as the house is seriously drafty and with solid walls has a high heat loss.

Tony

 

[DaveApp]

We still don't know what kind of boiler he has. Reduced flow temps opnly give a bit of saving with a condensing boiler.

Right now we have an old Ideal Classic which is well due for renewal. We want to replace it with a combi so we don't run out of hot water as the kids get older - it's already becoming a problem. So, as far as boilers are concerned, I'm open minded. Until today I'd never heard of Intergas, so any recommendations are gratefully recieved.

The other thing with a combi is that it will clear space in the loft should we decide to convert it at a later date. I'm looking to overspec the combi to accomodate the possibility of a loft conversion.

As far as building costs are involved, the floor could just be insulated without having to take it all up in most cases or without taking any up if there is adequate crawl space underneath.

We're going to be replacing the flooring completely downstairs so will be getting at least as far as the floorboards and considering the rewiring and plumbing that will need to be done, I suspect it would be quicker to have the lot up for ease of access.

most builders will then prefer to recover with chipboard ( Ugg ) rather than have all the work of refitting the boards.

Bearing in mind that you're talking to a layman here, what's the problem with chipboard?

Thanks for the input here. All of these points are giving me alot of food for thought.

Dave.

 

[muggles]

How big is your house? Even an overspecced combi will only do one bathroom....

 

[DaveApp]

How big is your house? Even an overspecced combi will only do one bathroom....

1930s three bedroom, 1 bathroom right now. No on-suite or any thing fancy like that. I was going by various websites saying that combis could cater for up to 2 bathrooms. At the end of the day if that's not possible and we do go in to the loft, we can always throw an electric shower up there.

 

[muggles]

A combi and electric shower would be better, even the mighty Intergas 36kw will only give you 13-15 litres per minute of usable hot water in the winter when the supply is cold. Split that between two bathrooms and it's a bit pitiful

 

[Agile]

Bearing in mind that you're talking to a layman here, what's the problem with chipboard?

Thanks for the input here. All of these points are giving me alot of food for thought.

Dave.

When laying a floor there is nothing wrong with chipboard.

Cheap and quick to lay.

But if any work is needed underneath, find a pipe leak or any electrical work and its a pain to take up to look underneath.

Being 600 mm x 2400 mm they are big sheets! Also tongued and grooved. So to take up without damage have to start at one end of the room and work across lifting all of them.

Compare with a 150 mm wide floor board they can be lifted and cut anywhere along their length. Relatively easily!

Floorboards can also be sanded and varnished or painted. You would never want to do that with chipboard!

Tony

 

[DP]

• Compare with a 150 mm wide floor board they can be lifted and cut anywhere along their length. Relatively easily!

I can do the same with chipboard. In fact, I can cut any size hole in the chipboard floor for access and no creaking afterwards.

OP, go with underfloor, you will not be disappointed. Reheat time is not that snail paced that it needs 'several days' to come up to temperature. I installed full spec UF for my boy and now he is a convert

His present house has solid base so Lo-Pro is a consideration. I am at present replumbing the installation to take in the extension and running pipes to proposed location of UF manifold. Pipes will also be laid for unvented cylinder (should he go down that route). Boiler I chose is Ideal Vogue. Controls will be Honeywell Evohome