Underfloor Heating Questions Water

[sotal]

I'm about to have a conservatory fitted which is just over 5m x 3m. As part of this I'm having a new boiler fitted as it's in the way at the moment.

The builder who is doing the base and walls etc has just asked if I want underfloor heating, and I hadn't thought about it at all!

I've heard that it's cheaper to run than most types of heating and could make the conservatory a much more comfortable place so we'd use it more and get better value for money.

So first of all the plumber has spec'd up a Glow-worm 24Hxi Boiler to Replace our Ancient Glow-worm Space Saver 38. Is that a good replacement? I'm trusting him there as I have no idea! We've got a boiler scrappage scheme voucher which makes things cheaper!

Our house is a 4 bedroom detached.

Also would the boiler be suitable and up to the job of also doing underfloor heating? We asked for it to be spec'd up to do 2 extra radiators so hopefully will have enough capacity.

And final question are there any good / bad UFH kits to avoid/go for?

We also have a utility room and downstairs toilet which I will be redoing once this is complete, these could also have under floor heating (currently have no heating). Not measured but I would say together they are no more than 10m2

I initially found this kit:

http://www.floorheating.com/products.php?CAT_ID=51&SUB_ID=53&P_ID=286

Which I thought maybe looked a bit weak? Would it be OK for just the conservatory? The price is what attracted me!

I then wondered if something like this would be better:

http://www.floorheating.com/products.php?CAT_ID=51&SUB_ID=53&P_ID=289

It does upto 30m2 (22.5m2 using closer pipe layout) and is in 2 zones so should be able to do the conservatory on one zone and the toilet/utility on another.

It just seems to be lacking info, is it all set mechanically in effect like another radiator? Would this be sufficient?

Any other tips etc?

Many thanks

 

[Agile]

I think its unlikely that UFH will give enough heat output to provide anything other than backgrouns heating.

Due to its different heating characteristics it would need seperate controls and timing.

Remember what I am telling you in case I need to tell you "I told you".

Tony

 

[sotal]

What would you recommend then?

If it helps I was considering also installing an air con unit in the conservatory which also acts as a heater.

Do you have any idea in terms of kw's how much heat is required?

 

[Agile]

The heat loss all depends on the construction of the floor, walls and roof.

If it was mine I would probably fit fanned rads so that whenever I wanted to use it I just turned them on but did not waste any heat when it was not occupied.

UFH only gives a amaller heat output and this is usually insufficient for smaller rooms in the house. It all depends on the insulation though and how its designed and fitted.

We would all advise you do NOT use your builder as the heating designer. Use a competent heating engineer instead!

A reversile aircon is not a bad idea but quite expensive.

Tony

 

[sotal]

Thanks,

Obviously the main room to heat is the conservatory, the utility room and toilet would be perfect to just be background heating, but I would really want the conservatory to be heating up quite well from the UFH.

The builder won't have anything to do with the heating, he was just asking if we were having any!

All I know so far is that we will have 4" of insulation under the floor, did have a name but can't remember it, I think he said it was silver backed?

The dwarf walls will be thermolite plastered walls.

The conservatory is South facing and will get direct sun from about 10am until sunset. (on the days we see the sun!)

I like the thought of UFH as it removes the need for a heater/radiator on the wall but am now concerned by your advice, as I don't want to spend money on something that won't work right!

 

[njk]

Hi Sotal,

UFH will be able to heat up your conservatory, but only as long as it is done properly, as with the insulation. It is not a diy job, even if some manufacturers claim so. I would make sure it is on it's own circuit with it's own timer as well. In regards to the utility and cloakroom, it will be a nice floor warmer but due to it's small active surface area you are very unlikely to heat the room on a cold day. But if you are installing ufhanyway, it's nice to add it in these rooms to take the chill of.
If you have 2 loops on the ufh, be vary of having a massive difference in the length of the loops. You can and should balance the loops, but when you have one loop that is 10m and one that is 100m you will never get a good balance.

In regards to what kit to use, spend the few extra pounds and use a good company, like Continental or Uponor (unipipe) and get them to recommend an installer for you.

Lolli

 

[sotal]

So you think it's a job for a pro only?

If that's the case I probably can't afford it! We've already spent 1000's (or ordered anyway) for the conservatory and the boiler move, I just figured if I could put it in myself for around £500 then it would be worth doing.

You say the insulation isn't a DIY job, are you talking about the 4" of insulation that the builder is putting in?

 

[Agile]

Its amusing to me how you ignore my warning about heat output!

Certainly you CAN fit UFH but the essential is to know how effective that will be. It would be fine if the heat loss was the same as a normal dwelling. I think it could be done by a competent DIYer but I would suggest a budget of closer to £1000 just for the bits.

You mention dwarf walls but dont say what else there is. I am guessing that its then a glass wall and ceiling construction. Thats likely to have a very high heat loss and I dont expect that UFH will be adequate. I dont know what a typical heat loss would be but I would expect quite high. Do you know anyone with a similar conservatory which you could measure? Does anyone have any typical measured figures?

Also be aware my perception is that people expect to spend a lot of time in their new conservatories until they are built and then they they use them during the day.

It amuses me that they dont realise in advance that after dark they are like goldfish in a bowl and visible to their neighbours. They then get a quote for screening blinds but find they are £2000!

Tony

 

[mointainwalker]

@ sotal

Has anyone done a heat-loss calculation for your conservatory ?

If yes, what is the amount of heat required to heat it ?

Given that it is likely to have very large areas of single-layer glass, you may be astonished at the amount ( cost ) of energy required to heat it.

Before wondering which type of heating to choose, you need to establish which types are suitable .

I agree with Agile (!!) about how many people seem to dramatically over-estimate the use they will get from their conservatory.

If you are also considering air-con you are obviously aware of the dramatic summer overheating problem, especially S-facing.

So air-con in summer, heating in winter: sounds to me like you're setting yourself up for some horrendous bills, apart from the cost of maintaiining these systems.

P.S. Have just had a look at your first link and I don't understand how it works.

It apparently uses the return flow on a rad circuit but as it says, this could be around 70 C. Since the input into a UFH circuit would be 45 C max ( regulations say max floor surface temp not exceeding 30 C ) and there is no mention of blending valves ( as there is in the second kit ), how it lowers the water temp is not clear to me.

If you are interested in this, be sure to clarify this point with the installer before they buy anything.

 

[DeltaT]

Why not use a split unit AC/Heater. We fit loads of these;
http://www.cooleasy.co.uk/product_wall.htm
The down side is it de-frosts for a few minute now & again.

If your conservatory is designed to be a 'heated' one then UFH is the best.

 

[sotal]

Its amusing to me how you ignore my warning about heat output!

I certainly didn't ignore your warning, I find it slightly odd that you think I ignored it when I expressed it as my main concern in the post that followed yours! I've seen you on here for years and respect and appreciate your advice, please don't think I ever ignore any advice. I take everything in!

You mention dwarf walls but dont say what else there is. I am guessing that its then a glass wall and ceiling construction.

Double glazed windows, one pair of double glazed doors and a polycabornate roof. The conservatory fits into a corner so two sides are walls, so it only has two sides of windows.

Do you know anyone with a similar conservatory which you could measure? Does anyone have any typical measured figures?

Don't know anyone with a conservatory just like this but some of the neighbours have conservatories so I can ask them how they fair in the sun etc. Would be useful if anyone has any typical values.

Also be aware my perception is that people expect to spend a lot of time in their new conservatories until they are built and then they they use them during the day.

We don't expect to spend a huge amount of time in there, one of the main points is that it joins two parts of the house which currently we have to go outside to get to - if that makes sense. Of course we hope to use it some of the time and it will be a great additional space for the kids.

It amuses me that they dont realise in advance that after dark they are like goldfish in a bowl and visible to their neighbours. They then get a quote for screening blinds but find they are £2000!

Not overly concerned as we have open fields to one side, a wall to two sides, and the other side would only looked over by our neighbours behind if they're standing in their garden, I'm not planning on doing anything in there that I wouldn't want anyone to see


Again - thanks for your help & advice

 

[sotal]

@ sotal

Has anyone done a heat-loss calculation for your conservatory ?

If yes, what is the amount of heat required to heat it ?

Given that it is likely to have very large areas of single-layer glass, you may be astonished at the amount ( cost ) of energy required to heat it.

Before wondering which type of heating to choose, you need to establish which types are suitable .

I agree with Agile (!!) about how many people seem to dramatically over-estimate the use they will get from their conservatory.

If you are also considering air-con you are obviously aware of the dramatic summer overheating problem, especially S-facing.

So air-con in summer, heating in winter: sounds to me like you're setting yourself up for some horrendous bills, apart from the cost of maintaiining these systems.

P.S. Have just had a look at your first link and I don't understand how it works.

It apparently uses the return flow on a rad circuit but as it says, this could be around 70 C. Since the input into a UFH circuit would be 45 C max ( regulations say max floor surface temp not exceeding 30 C ) and there is no mention of blending valves ( as there is in the second kit ), how it lowers the water temp is not clear to me.

If you are interested in this, be sure to clarify this point with the installer before they buy anything.

No we've not had any calculations done. WHo would we get to do that? Would that be the company building the conservatory? Or would we need a heating specialist in for that?

I don't like the sound of horrendous bills! What do people normally do? My sister has a conservatory and just has an electric oil filled radiator in it, it's only a small conservatory but seems to heat it OK. Their's is north facing so doesn't really need cooling.

As for that first link, I'm not sure either and didn't really like the look of it, but posted it incase anyone said that would do the job! It says something about the return from it restricting the flow when it is too hot????

 

[sotal]

Why not use a split unit AC/Heater. We fit loads of these;
http://www.cooleasy.co.uk/product_wall.htm
The down side is it de-frosts for a few minute now & again.

If your conservatory is designed to be a 'heated' one then UFH is the best.

That looks like the kind of A/C unit we'd looked at,

What do you mean if it's designed to be 'heated'?

 

[Agile]

There are two kinds of simple a/c units and often ceiuling mounted and seen in restaurants.

The cheap ones have a cooling a/c and just electric heating elements to privide heating.

The more expensive ones have a cooling a/c and the reverses to operation to become a heat pump to provide heating.

Sorry to be a drag but in most cases a £9.99 2 kW fan heater is by far the cheapest way to heat a conservatory.

Most people I see hardly use their conservatory when the sun is not shining ( which includes after sun down ).

My mother had two "conservatories" but they were just three sided rooms with d/g windows on three sides, longest one was sliding patio doors. But the corners were cavity brick and the roof proper insulated space. So they were in effect rooms. She still only used them when it was light!

In theory it should be possible to calculate the heat loss but expect it to be high. There is an interesting planning or building reg situation that most conservatories I see had a condition imposed that they did not have permanent heating.

Tony

 

[mointainwalker]

@ sotal

Put plainly, if you don't know how much heat you need, how do you know how much heat to install ?

This is obviously crucial with UFH because the heat you get is based on the metrage of tube you lay and very obviously you can't alter that afterwards and you can't rely on some kit that says it does 15 m2 as much of a guide.

The heat loss calc should be done by the person who installs the system, so that if you tell them you want to have a temp of x degrees and the system doesn't give this, then it's their responsability to fix.

Were you considering heating the space at all before the builder brought up UFH ?

If yes, what type and how many kW ?

I actually think Agile's suggestion of the 2 kW fan-heater is far and away the best. Think of the cash that would save you !

@DeltaT

I'd be interested to hear about these "heated" connies as well, if you'd care to tell us ?