underfloor heating in a period property

[tegwen]

We have recently purchased an old stone and flint cottage, the property has what I believe to be limecrete floors throughout the ground floor level. We are considering installing wooden flooring with an underfloor heating system, however we are concerned that this could lead to damp problems due to the membrane that is required during the installation.
Any advice would be appreciated

 

[Nemesis]

Limecrete - or lime ash?

 

[tegwen]

Sorry very much a novice, how can i tell. The cottage is circa 1840 if this helps.

 

[Nemesis]

If the floor is old it's lime ash, historic, and desirable to have!

 

[Ian Bond]

This thread may be of interest. Not identical I admit, but all sorts of trouble with damp because an non breathable concrete screed has been applied to a direct-to-earth floor. Water is being forced up the walls and blowing plaster off. If timber skirting or panelling is present, this would be at risk of rot.

A solution is being attempted by replacing the cement and gypsum plaster at the base of the internal wall with a lime plaster, which should cope better with the damp.

http://periodpropertyshop.co.uk/phpBB2/viewtopic.php?t=8506&sid=05a12ed348118fae08596448bd36c73f

You are right to be cautious.

 

[alice]

I'm going to have my ground floor remodeled and I was investigating under-floor heating so I could get rid of the modern, ugly radiators that take up so much wall space. I looked at hot water underfloor systems, which are more efficient and could possibly tie into the present central heating system.

Well, I found out that after a suitable insulating underlayment was installed, the pipes and then the top cover and then the wood floor itself, the depth of all this would be about 20 inches. That's a good depth to try to blend in and would involved major reconstruction and I decided it wasn't worth it for me and I have 11 ft ceilings. Would you have to dig to get enough depth?

An electric system could be installed under wood or tile/stone floors, but from what I could find, electric underfloor isn't anywhere near as energy efficient as the wet versions (about half).

So I'm still mulling over the best heating system to use. Presently I have central (radiators) heating. Forced air, as is common here in the states isn't used much in the UK, electric units are expensive to run... it's a puzzle.

alice

 

[alice]

double post

 

[MdB]

Just to nick pick a little. All electrical heating is exactly 100% efficient when talking about converting electricity into heat. This includes underfloor electrical heating. Hot water heating is not 100% efficient as there are losses where the water is heated. However, the generation of electricity in the power station is only 50% efficient on a good day so electricity heating overall is less efficient than other methods which is why it costs more to run.

The most efficient way of heating a house is by heat pump (which is what we are going to have fitted) which can by 300% to 400% efficient (heat energy out compared to energy input) within the house and 150% to 200% efficient overall.

 

[AMc]

Of course heat pump installers will tell you it works best with wet underfloor heating (low temperature, large surface area) and we're back to square one for alice

We're planning on using underfloor heating and a heat pump (probably air source) when our renovations finally get under way and I'm going to have to find out too. I suspect the answer will be a lot of digging and limecrete.

I did have a quick look at this THERMASKIRT stuff for upstairs - basically a radiator shaped like skirting that goes around the room.
http://www.discreteheat.co.uk/better_than.html
If you're got original skirting you probably won't be interested, but if you're insulating the walls or your skirting is long gone it could be of interest. At least you get the wall space back from the radiator and the 'all around the room' heating does sound like a good idea.
It can't warm our ground floor (too much space, not enough wall) but may be a contender for the bedrooms.

 

[Penners]

THERMASKIRT

Sounds like a product for elderly ladies, from Damart.

 

[JMartin]

Folks...on the subject of the mighty heat pump...we spoke to numerous companies at the last homebuilding and renovation show and were seriously put off it as a viable solution.

All companies told us that they only sold the pump and we would have to employ a plumber to install it and provide the rest of the materials ourselves. We were also told that it would be nigh on impossible to install underfloor heating in the suspended wooden floors we have and be able to maintain a decent heat since we have a gale force wind blowing through our underfloor spaces..something we obvisouly want to maintain.

In the end we were quite dismayed so went to speak to the Rayburn chap who could sell us a new Rayburn and Wood Burning Stove for the same price as the Heat Pump. This will fit nicely into our house, be in keeping with the original use and provide us with plenty of hot water and heat. The stove would also heat the hot water, backed up by an emmersor. We're so convinced of this that we've taken the radiator out of the kitchen in preparation...it burst and well, have you seen the price of nice radiators these days! It'll be a cold winter but by next year we should be ready to install our new heating system.

Our house is a basic four room layout with one room at either side of the hallway on two floors. The plan is to put the Rayburn in the kitchen (which is presently the living room) on one side and the wood burning stove in the living room (which is presently the dining room) on the other side and let these heat all rooms. We will suplement this in the dead of winter with electric wall mounted heaters in the upstairs rooms and the bathroom (extension) and insulate the outside walls and loft to the maximum we can afford. It can't be any worse than our current open coal fire in one room and we will have avoided having to give a huge chunk of our house over to an unsightly pump. Everybody (impartial) I have spoken to about Rayburns says that the only time they've ever been warm in an old house was with a Rayburn.

We had our hearts set on the Heat Pumps as the most environmentally friendly solution so were quite upset for a while when we found we couldn't have one. Looking back though and looking at the space we have, I think it was the best thing to happen to us.

 

[MdB]

Heat pumps and suspended floors don't go together well as you have found. There are options but they are both expensive and don't work well. The heated skirting board option does look interesting though and will work with the lower temperatures of heat pumps though not ideal.

 

[ljn]

I also need to research a good heating system for a Georgian detatched house. The previous owner "did the house up". The heating system has an old looking combi boiler on the ground floor that feeds a hot water cistern on the top floor- so if you turn the hot water tap on in the kitchen, the boiler next to you comes on, but is feeding the water to the tank on the floor above... to do this it uses a very noizy pump you can hear in every room. And if you put the hot water on, it also feeds into the radiator system. So, aafter receiving the first gas bills, this summer we keped it off and boiled a kettle to wash up. Fortunatly there is an electric shower.

I looked into the geo heat pumps aand so far I've been told:

Geo heat pump systems are only efficient in modern "air tight" buildings where heating needs are minimal.

Traditional "ventilated" buildings need more a more aggressive heating system.

Geo heat pump systems efficiently heat water to a temperature much lower than traditional radiators require, but suitable for underfloor heating or in-wall systems. But if the building isn't sufficiently insulated and draft-proofed, it won't cope. Maybe you'd even get a big electruicity bill for the pump.

Also solar pannels also seeme to be expensive and not very efficient.

So I've got a lot of research to do and a cold winter ahead. I remember from when I was a kid that hats and gloves work well, and that the unpleasantness of a frozen towel can be offset by the beauty of frost patterns on the bathroom window.

 

[Flyfisher]

I've also been looking at heating systems and the more I read the less appropriate they seem to be.

Geo heat pump systems are only efficient in modern "air tight" buildings where heating needs are minimal.

. . . except that even modern 'air-tight' buildings are not really air-tight, indeed there are defined ventilation recommendations that suggest air-changes of up to 4 times per hour - as discussed in a previous thread - which doesn't seem ideally compatible with a 'low-grade' heating system such as a heat pump.

Geo heat pump systems efficiently heat water to a temperature much lower than traditional radiators require, but suitable for underfloor heating or in-wall systems. But if the building isn't sufficiently insulated and draft-proofed, it won't cope. Maybe you'd even get a big electruicity bill for the pump.

That's my understanding as well, which typically limits them to modern buildings unless you're prepared for lots of work remodelling floors of an older property. Our floors vary but are mainly tiles laid directly on earth and I've no great inclination to dig everything up and install some sort of slab with associated insulation and loads of piping.

Also solar pannels also seeme to be expensive and not very efficient.

I'd agree with this as far as PV cells are concerned, but I've read much better things about solar water heaters, particularly the evacuated-tube ones. I have no direct experience of them though.

So I've got a lot of research to do and a cold winter ahead. I remember from when I was a kid that hats and gloves work well, and that the unpleasantness of a frozen towel can be offset by the beauty of frost patterns on the bathroom window.

Me too. Personally, I'm beginning to consider not bothering with a central heating system at all as I'm starting to wonder if it's really worth the effort and expense of trying to keep the whole house at a reasonably constant temperature.

I'm currently favouring a Rayburn (or similar) in the kitchen, and multi-fuel stoves in the other (downstairs) rooms, to be used when necessary, which won't be constantly. I'm not bothered about bedrooms as we don't like them hot anyway (and always sleep with the windows open all year around) - although electric blankets are considered essential - and electric fan heaters (with an integral timer for cold mornings) seem to work quite well for the bathrooms.

And, as rightly stated, an extra layer (or two) of clothes can make a huge difference in their own right for the relatively few weeks of really cold weather that we have these days (in the SE anyway).

Perhaps the longer I prevaricate, the more I get acclimatised to the cold weather. After all, Spring is on it's way so who needs central heating anyway?!

 

[MdB]

Geo heat pump systems efficiently heat water to a temperature much lower than traditional radiators require, but suitable for underfloor heating or in-wall systems. But if the building isn't sufficiently insulated and draft-proofed, it won't cope. Maybe you'd even get a big electruicity bill for the pump.

That's my understanding as well, which typically limits them to modern buildings unless you're prepared for lots of work remodelling floors of an older property. Our floors vary but are mainly tiles laid directly on earth and I've no great inclination to dig everything up and install some sort of slab with associated insulation and loads of piping.

To make it sensible to fit our heat pump + underfloor heating we are also replacing the floor (with lots of insulation in it) and some of the walls (with good insulation too) and insulating most of the remaining walls. This work would be rather OTT if it was required just for the heating system but it's needed anyway for structural and other reasons.

Heat pumps are good but only in the right situation.

 

[Flyfisher]

I'm an 'open door' as far as the concept of a heat pump is concerned and started out thinking it was the answer to my needs; a 'gentle' background heat, relatively economical and, therefore, reasonably environmentally friendly. But ljn's post struck a chord with my research into heatpumps and I also ended up disappointed with what I found, which put me off the idea. I'd love to be proved wrong though!

I guess you have the 'advantage' of requiring the floor remodelling for other reason, which should certainly help to justify the capital costs. It would be great to hear how the systems works when all the work is complete (or from anyone else who operates a heat-pump based system).

 

[JMartin]

I'd love to be proved wrong though!

Me too. Unfortunately I think your research has hit the right answers. Several heat pump salemen told us that the system was no good for our house and they prefer to install them in new builds.

 

[KN]

Had our heat pump running nearly a year now. All snug here, under floor heating on the ground floor and cast iron rads on next 3 floors.
No regrets.
:wink:

Karen

 

[MdB]

Had our heat pump running nearly a year now. All snug here, under floor heating on the ground floor and cast iron rads on next 3 floors.
No regrets.
:wink:

What temperature do you have coming out of the heat pump to run the radiators? I thought that radiators + heat pumps wasn't a good idea at the rads like 70°C and heat pump produce 40°C. The heat pumps can be set to produce a higher temp (I believe) but the efficiency goes down.

 

[KN]

The heat pump tell me it is running at 30 deg for the radiators upstairs at the moment. It is adjusting itself with an indoor sensor and an outside north facing sensor. It just gets on with it giving a constant room temp that I've set it too. We have two old radiators per room with single glazed sash windows and the house is of stone construction.