Underfloor v Rads

Macy · 27-07-2004 10:00am #1

Planned to put in underfloor heating into the house rather than the conventional rad system (new build, starting soon hopefully).

As well as the obvious aesthetic advantages of the underfloor heating, I was under the impression that while it was more expensive to install, it was more efficient to run - lower water temperature, heating the air space where needed etc.

However, talking to a few people (builders), in their experience it's not only approx half as much again to install, it is also more expensive to run. They cite the need to heat up the concrete slab, and leave the heating on all day to avoid a total start up.

I'm hearing both ends of the spectrum of views, and decision time is looming! Any help would be greatly appreciated!

Also while I'm on heating, anyone have experiences of the cremin tank? If the blurb is to be believed it would solve a lot of the issues that people are telling me about underfloor heating, as well efficiency savings for a rad system.

Thanks.

GlennaMaddy · 27-07-2004 10:07am

Yes, I've heard some negative comments from builders on underfloor heating too. The builders were not involved in the project so I trust their opinions are unbiased.

I self installed a DEVI underfloor system in the upstairs bathrooms (tiles can be cooooold in the morning). This is way cheaper than having underfloor heating plumbed and I have seen no change in my ESB bill.

Lex Luthor · 27-07-2004 11:48am

spoke with an architect lately and he doesn't think its a great idea. Probably in one or 2 rooms like bathrooms but thats all. You can get some really nice rads these days...

Victor · 28-07-2004 4:30am

Underfloor takes up less space (but more "height").

No clutter - no planning furniture around rads.

Nothing to bang heads and knees on.

No need to paint in X years time.

Lower operating temperature (about 26 degrees) - no scalded toddlers.

No frozen toddlers from sitting on the floor.

No frozen floors in the morning - if you remember to set the timer.

Dries mopped floors better.

Better heat distribution in the room.

Slightly more difficult to put in at the start, but *must* be done right - this is where builders will object.

PBC_1966 · 28-07-2004 10:08pm

Underfloor heating (electric variety) was quite popular for new homes in England in the late 1960s/early 1970s.

These days, many of those systems have been abandoned and replaced with other arrangements.

One of the biggest problems with the British/Irish climate is that the concrete floors act in much the same way as storage heaters, making it effective in the depths of winter when you know heat will be needed all day, but very difficult to control during those times when the weather swings from warm to cool and back again with alarming regularity. If you run the underfloor heat from a hot-water furnace system, you'll get better control than with night-rate electric heat, but the time lag is still going to make it harder to control.

PH01 · 30-07-2004 10:17am

Go for underfloor.
I got installed in the house I've built, and it great. Well worth it and I'm glad that decided to do so.
I have it downstairs only as I don't like the heating the the bedrooms where I have rads.
Builders will tell you anything as long as it's easier and cheaper to install. So don't get pushed around by them.

yop · 30-07-2004 10:41am

"Builders will tell you anything as long as it's easier and cheaper to install"

That is for sure. I have a number of mates who have installed underfloor and would never go back.
One of the main reasons is the lower operation temp which obviously is cheaper.
We have building a 2500 sq ft house and the cost of the underfloor for both floors is under 7k, this is roughly about 30% dearer than putting in rads.
I for one would not touch rads, but everyone is different.

BTW - Warmfloor are the best I have found for experience and cost if u are looking for a company to do the job

Macy · 03-08-2004 9:28am

Cheers lads. Good to hear the people that have it wouldn't swap back, although PH01 any particular reason you didn't go for it in the bedrooms (bungalow that we're building, so bedrooms ground floor too)?

Anyone heard any reports about the cremin tank/ oxyvent (http://www.oxyvent.com/index.htm )? Seems excellent in theory, and seems to solve the heating up of the slab problems for the underfloor. I remember seeing it installed in a few of the "about the house" houses, but ultimately not sure I trust Duncan Stewart as he just loves new gadgets....

yop · 03-08-2004 12:08pm

"Anyone heard any reports about the cremin tank/ oxyvent "

Nope, never heard of it. If you based ur underfloor decision on this lad u would not go near it!!
I will ask around and see if anyone has put it in

I got a good mag called "Self Builders" and it is an Irish magazine there in centra the last day. Would recommend it.

Carapello · 07-08-2004 2:21pm

My house has both rads and underfloor heating. The underfloor heating is great for the bathroom becasue there's no more cold tiles underfoot.

zep · 16-08-2004 5:43pm

Anyone thought of using Geothermal Heating System.
Got a quick quote of 10K for 2100 sq foot house. With running costs on 400 yoyo per annum.

beolight · 13-02-2006 9:56am

http://www.oxyvent.com/underfloorheating.php

the cremin/oxyvent box

has anybody incoporated this device into their heating systems yet?

if so any feedback?

Cushtie · 13-02-2006 11:22am

Going for underfloor aswell. in fact the piping is being laid tomorrow for the ground floor. it is costing around €8K for a 2600 sq ft house (both floors). However I have still not fully decided on if it will go on in upstairs aswell.

I am really confused here. most people tell me there is no need for it upstairs, even the UFH sales man said as much. then I see some people who would swear by it.

A few users here on boards have done it in all the house (Yop our resident expert!!!).

thing is I may have to go for oil as the budget may not stretch to a geo heat pump but if in say 5 - 10 years I decided to put in the Geo Heatpump / solar etc would having radiators on the upstairs really count against this??

any advice would be really appreciated as it is coming close to decision time

PS. Macy sorry I hijacked your thread

Carb · 13-02-2006 11:58am

Cushtie wrote:

Going for underfloor aswell. in fact the piping is being laid tomorrow for the ground floor. it is costing around €8K for a 2600 sq ft house (both floors). However I have still not fully decided on if it will go on in upstairs aswell.

I am really confused here. most people tell me there is no need for it upstairs, even the UFH sales man said as much. then I see some people who would swear by it.

A few users here on boards have done it in all the house (Yop our resident expert!!!).

thing is I may have to go for oil as the budget may not stretch to a geo heat pump but if in say 5 - 10 years I decided to put in the Geo Heatpump / solar etc would having radiators on the upstairs really count against this??

any advice would be really appreciated as it is coming close to decision time

PS. Macy sorry I hijacked your thread

I'm putting it in on both floors. The no. 1 reason for this originally was because I was going for a heat pump, and obviously, a heat pump doesn't work as well with radiators. I'm not sure at this stage whether I can still afford the heat pump, but I simply don't like radiators, so why would I settle for them upstairs. Plus the UFH pipes are buried in 2 inches of sand and cement upstairs, so the sound proofing will be greatly improved, although you don't need UFH for this. On the cost side, radiators would have cost the same if not more. My house is 3000sqft and my plumber is doing the UFH and all the plumbing for 10k. Boiler/heat pump will be on top of this.

iplogger1 · 13-02-2006 12:30pm

Just in relation to costing:

Zep mentioned an estimate of 10k for UFH/Geothermal. I assume
this is the cost of the UFH system + installation and doesn't
include the geothermal collector/excavation/filling/heat pump.
Yop did a lot of research on systems/costings and he got the
combined capital costs down to about 18k.
Personally I am getting cold feet (excuse the pun) about geothermal
and I need more convincing when I see some return on
investment projections. It is the electricity running costs which
concern me and as I understand it the pump probably needs to
do a good deal of work during summer to return heat to the
ground (correct ? I'm not sure of my facts here).

I think 400 Euro p/annum running costs for geotherm/UFH for
say a 2100 Sq ft is very understated (but that is just based
upon real usage figures I've heard from folks who've installed
geotherm .. but it is early days with them to say how it pans
out over a full calendar year).

It was asked whether plumbing in conventional rads would
go against installing geothermal at a later date. Geotherm
is only going to work efficiently with UFH and I'd not be
happy about digging up the garden 5 years from now to
retrofit such a system.

~ipl

tcoen · 15-02-2006 2:46pm

The heat pump does not "recharge" the ground during the summer, the sun does that. The ground is one big solar collector heated by the sun. Geothermal is abad name really. Ground source heat pump (GSHP) is better.

Unless you have 12K under the mattress you'll be borrowing the money for the heating source (GSHP).
Now lets say that the heat pump has a life of 15yrs. You'll need to borrow 12k over 15 yrs to repay the capital cost of the heat pump (pump may last longer in practice).
Lets say that costs 1000 euro per year.
Then to get a rough estimate of the esb costs to run the thing as sq. m of house by 2.6 euro so for 210 sq mtrs thats €546. Domestic hot water heating may add to this but not massively.
So you need to find approx 1600 euro each yr for the bank and esb.
Now how much is the repayments on a 2000 euro boiler and the amount of oil your buddy in a similar house down the road uses?
Average oil bill in Ireland according to sei is €1300

prospect · 15-02-2006 3:21pm

I have underfloor heating d/stairs and rads u/stairs in our house, built 1.5 years ago.

TBH, It has been a disaster so far. Although I would not blame 'underfloor heating' in general, I can't help but think if the whole house had been rads we wouldn't have had any problems.

prospect · 15-02-2006 3:40pm

Actually can I ask the people here who have underfloor installed (especially those with Rads upstairs), do you have your oil burner on 24/7, or do you have it set to burn at specific time intervals?

squire1 · 15-02-2006 5:06pm

I made the decision to go for rads throughout the house. At first I was all up for going with UFH but a lot of little pieces of information from people in the building game whom I know and trust made me change my mind.
I'm not saying that there is anything wrong with modern UFH systems it's just that I was not prepared to take the risk on someting with a high capital expenditure if I was not 100% sure I would be happy with the finished product. I'm a bit of a chicken really and I'm sure I'll probably regret the decision later but it was a decision that had to be made and I went with the safe option. It's all down to personal preferance but they key is to do as much research as possible and make an informed decision.

iplogger1 · 15-02-2006 5:27pm

Just to reply to tcoen's message regarding the borrowings and esb running costs of the GSHP compared to conventional oil burner capital and running costs.
Looking at the guide figures you provide there isn't much in it unless we make
the assumption that oil prices will accelerate at a rate divergent to those of ESB costs (ESB power generation increasingly via gas turbine technology).

I'm also a tad sceptical of the 546Euro p/annum heat pump elec running
costs (which I assume are based upon that PDF file mentioned in another
thread from www.geothermie.de website using 2.6Euro per m^2 guide).
I'd love to hear from real people within Ireland who have this system
installed for a full four seasons or more and who have totted up their
electricity consumption by the pump over that period). I've just one
reference to go on so far and he has it in only one season (the coldest)
but he is struggling to get pump to run for under 4Euro per day at best.
Maybe that dramatically goes down in summer but I'm not sure about
that. I'd imagine there is some minimum duty cycle (or whatever) on
the heat pump which must be delivered by it all year round.
Also the cynic in me says that ESB charges here in Ireland are probably
quite uncompetitive compared to the rest of Europe for domestic
but I could be well off base there.

~ipl

Boggle · 15-02-2006 5:43pm

I know a guy who's house is being used to test a new underfloor heating system developed by a local crowd (Clonmel, Tipp) and he reckons his system is the job. Installation pumps are supposedly similar to a conventional system (Although I don't know how much that it tbh!!) Not sure about running costs but he reckons that its similar to a heatpump even though it runs 24 hours a day.

Not sure if its released yet but if you want to find out PM me and I'm sure I can get a number - suppose you cant lose by checking...

ANyway, good luck!!

dderd · 15-02-2006 11:17pm

I've decided to put in UFH everywhere except b/rooms, reason being that I don't think its healthy for b/rooms to be too warm. I am worried about running costs though and am I losing out on the economic benefits of UFH heating running at lower temps by rads needing high temps. I've spoken to the plumber about this and he thinks the combination of rads & UFH is best but advises running costs are more expensive - not because of using both but just because he thinks running costs of UFH is higher. This is not what I read in magazines etc.... so am confused.

yop · 16-02-2006 11:12am

Ask him on what basis is UFH more costly to run. Maybe I am totally naive but how could something that runs at 1/2 the temperature be more costly to run.

If you get a chance ask him "But if UFH runs at about 40 degrees, and rads run at about 70 degrees how can the UFH be dearer to run?"

I think with you installing rads and UFH you are going to spend as much, if not more than installing one or the other. Correct me if I am wrong but you will need pipes for the UFH both upstairs and downstairs? You will need 2 manifolds for this & circulating pumps. You will need a feed and return from your manifolds for the UFH and for your rads.
Then you will need the piping for the rads both upstairs and downstairs as well as the rads themselves.

It is possible to turn down the flow on the UFH for each bedroom as well as having thermostats.

Maybe I am wrong but he probably thinks that installing both is because he can charge more. Maybe I am too sceptical

prospect · 16-02-2006 11:36am

Is it not more expensive to run because it is heating to 40oC 24/7. Where a standard system heats to about 70oC for about 8 hours a day?

It is very hard to get straight answers on this subject.

1. Do you have under floor & rads?
2. How many square feet are you heating?
3. What temperature is your boiler set to?
4. If answer 2 = 40oC, do you not find the tap water a bit too cool?
5. Is your boiler on 24/7?
6. How many litres a day do you burn?

I would really appreciate if people here could answer these questions as i am in a dilly of a pickle with my system. Here are my answers:

1. Underfloor downstairs, and rads upstairs
2. 1500sq ft downstairs & 1300sq ft upstairs
3. 45oC
4. Yes, it could be warmer
5. No, it burns for 2 hours three times a day, and 30 mins on 1 hour off thereafter
6. 36L a DAY :eek: :mad:

Cheers
Prospect.

patrido · 16-02-2006 1:26pm

it's very hard to find good facts and figures for the running costs and efficiency of ufh systems. in my opinion ufh is a luxury. it's benefits are comfort and aesthetics. it should not be put in because some sales person tells you it's cheaper to run. i have seen examples where the running costs are low. but i have also seen lots of examples where it's costing a fortune.

all anyone planning for ufh can do is pay lots of attention to the design, in relation to their own particular requirements, and then hope it will not be too expensive to run.

a few points -
1: while ufh runs at 40 degrees versus 70 for rads, there is a greater volume of water to heat to this temp. my system will contain about 110 litres in the pipes. a rad system would contain much less. the 40/70 argument is simplistic and overused by ufh companies to help sell their systems.

2: the on 24/7 issue is another red herring. how can a policy of never-turning-off-the-heating possibly make any system cheaper to run? all it does is eliminates the long heat up time, at a massive price. in my opinion, setback is the only effcient way to run ufh, and have reduced heat up times. if anyone has a ufh system that does not have setback controls, throw them out, and buy better controls. weather compensators can also increase the efficiency.

3: design. the location of your pipes are principally determined by the occupancy patters of the house. for full time occupancy, pipes in a large 100-150mm slab installed before the walls is a very efficient option. it will have massive heat up times, but this should only be once per heating season.

for houses where the occupants go out to work every day, pipes over an insulation layer, above the concrete subfloor, and below a thin screed (anhydrite based for even quicker heat up) is the best option. this gives a quicker heat up time, and even quicker setback-to-full heat time. unfortunately a lot of people allow others (builders and plumbers) make important decisions on their ufh based on what suits the builder not the home owner.

4: boiler cycling. having the boiler going full to keep the ufh going is a complete waste also. my system will have a 35kw boiler, but the max ufh requirement is 12 kw. so on a average spring day, with a few rooms on and a few off, i might only need 2 or 3 kw to keep the relevant rooms warm. no point having a 35kw boiler trying to supply 3 kw.

boilers are at their most efficient when burning on long cycles. for this reason i'm putting in a 400 litre thermal store, which will heat up the water once per day, and only need a very occasional top up. this is even more important for heat pumps, to take advantage of night rate leccy. another alternative is to have 2 smaller boilers rather than one big one.

iplogger1 · 16-02-2006 1:47pm

Padrido,

Excellent information !

I assume your heatpump is GSHP ? (or is it a bored well or other ?)

Can you elaborate a little bit on the principle of setback controls. I think I know what they are but I could do with your articulate enlightening on this

Also (and hopefully not too much of a red herring) - I've seen this 2.6Euro
per square meter per annum ballpark estimate for houses around 2000 sq
feet or so being bandied about as a v.rough estimate of electricity consumption by a GSHP. It came from some European eco whitepaper on geotherm systems. I'm wondering if domestic electricity is more subsidised in mainland Europe .. also it tends to be more nuclear generated in France. I'm early into the research of the potential running costs and a lot boils down (no pun intended) to the design of the system as you outline in your post.
However, this figure of say 540 Euros per year versus 1300Euro to heat a house using a conventional oil boiler sounds very optimistic to me from just anecdotal chats with folks who have these systems installed (early Irish adopters)

~ipl

patrido · 16-02-2006 3:00pm

setback just means that instead of letting a room cool completely during the "off" period, it is maintained at a lower temp. the offset varies from one stat to another, but its usually around 7 degrees. the idea is that it's much easier to heat a slab up from 13 degrees to 20, than from cold.

tcoen · 16-02-2006 5:14pm

More propaganda:
http://www.ahac.ie/site/casestudy.html

tcoen · 16-02-2006 5:31pm

http://www.askaboutmoney.com/archive/index.php/t-2841.html

iplogger1 · 16-02-2006 5:51pm

Very interesting thread (on AAM) there TCoen.
I must read it more carefully later this evening.
I notice a poster (heinbloed ?) making some
very interesting points especially re: suppliers
ball park figures against perhaps looking at
2 season minimum electricity bills from a domestic
user of GSHP/UFH.

thanks for that. I'll use my salt pincher when reading
the propaganda links but they are interesting
nonetheless.

~ipl

patrido · 17-02-2006 9:37am

http://markbrinkley.blogspot.com/2006/01/just-how-good-are-heat-pumps.html

Underfloor v Rads

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