Underfloor heating running costs - help

corkcuu

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Have done searches but not finding answers in relation to this.
We moved in to our new house in june - had to refill the oil tank 2 weeks ago and we checked it at the weekend and its half gone already - it has used 450litres in 2 weeks!!

We have underfloor heating down stairs & rads upstairs. As we were off work over the hols the UFH was switched on from 9am - 11pm. Upstairs rads were only on for approx 2 hours a day.
PLEASE PLEASE PLEASE tell me this is not the norm for UFH. To me it means there must be a problem??? Any help or advise would be greatly appreciated on this.
 
Oh theres a problem and suddenly the UFH is to blame, it all depends on the size of your house really and if theres any drafts. Maybe theres a leak in the pipe, UFH is designed to run at 20 - 22 degrees, I think there are major problems when you mix UFH and normal rads. In my opinion its a very bad idea.
 
I am not blaming the UFH but my problem is that spending €400 on oil in 2 weeks must signify a problem somewhere.

Our house is 2800sq foot. No drafts. The rads are running at 20, however the UFH is only running at 18 downstairs.
How can we check for a leak?
 
Is the tank easily accessible? There have been cases in my locality of certain nefarious individuals siphoning heating oil from homes into concealed tanks in the back of vans etc.

Just a thought.
 
remember you're looking at a money amount, not an oil qty. Oil has gone through the roof, so you're getting less and less oil for the same amount of money..........the heating system, whatever way it's set up, is probably more or less constant.....

But it's still worth getting your system checked out.

Personally, it sounds like your heat is on too long, per day. My ufh, which I'm still fiddling with, is on 06:30-07:00, 12:00-12:30 and 16:30-21:30.

I'm with Joe Hooker - rads + ufh are a nightmare. The boiler needs 60 deg water for rads and dhw, and only 30-40 for the floor. Very hard to get the thing sync'd correctly.
 
Hi Corkcuu

Running your system from 9am to 11 pm will def cost you more. Besides the obvious i.e. house size, desired temp, insulation, glazing etc. etc. that influence the heating costs, the amount of time you run the system will have a significant impact on costs.

For example in my home I have 160m downstairs on UFH and 90m upstairs also UFH.

I turn on my boiler for 3 hours for downstairs and 1 hour upstairs at this time of year. As the return water never gets to 60 C (my lowest setting on my Firebird 120) the boiler remains on continously.

Costs

4 hours @ 3.1 litres/hour (the oil flow rate for the boiler) = 12.4 litres per day

On this basis I will get 80 days from a 1000 litre tank of oil for €690.

Some days the heat requirement is higher and other days lower. It depends on the outside temp and sunlight.
 
Hi corkcuu,

There may very well be a problem with your system so it might be well worth your while getting your installer to come back and check it out. Have a good record of how much oil was used- when you bought it, how many litres, when you refilled again. It's better to have hard facts rather than saying 'That bloody UFC is drinking oil...!'

But just to give you a glimmer of hope....
I'm in my second winter in my own house. We moved in around August 2006 and for that first winter I was watching the oil usage like a hawk- and I nearly had heart failure!!!! From June 2006 to June 2007 around 3000 litres of oil was used! Everyone I asked about this said it was normal as the house was still drying out which will mean a higher than normal heating requirement and so more oil is burned.
This winter the usage is way less- I put 1000 litres in the tank in October and there is still 1/3 of it left. And the house has been toasty the whole time. So it seems as though the system has settled down.

Best of luck in your new home!
 
Thanks guys, starting to breathe a bit easier now. Going to get it checked out alright still cos even though we had it on a lot I feel it is using more then it should.
about the timing we were told by plumber & electrician we should leave it on 24hrs as once the temp sensor reaches the temp it automatically does not look for anymore heat but from reading the replies that doesnt seem to be the case. So should we use it same as radiator heating - on for just a few hours every day?
 
To maintain a constant temp it's better to leave the system on all the time and let the stats call for heat as required but this is a much more expensive way of heating imho. A few hours everyday would be my preferred option. Unless it's below below zero all day outside my indoor temp drop from a 3 hour heating is about 20c to 17 c over 21 hours. Heat on from 5 am to 8 am - house warm getting up in morning - throughout day and into night and drops down while sleeping.
 
Thanks for that Ted. Going to try doing it that way and hopefully will see an improvement.
Also your costs calculation above is a huge help.
 
i know this is a different thread but i recentley got ufh in when i bought my new house. The floor in our kitchen/dinning area is tiled but there's seems to be no heat at all.. I have the heat on at constant and the temp is at 22c. I thought the tiles are meant to have a gentle heat to them but they are freezing. Any idea's or does anyone know what am doing wrong?
 
I have UFH and Rads upstairs. Used 1200 litres of oil in my first fill in 6 weeks. (on 13/14 hours a day) This is my second winter and the oil usage has dropped to 1200 litres/16 weeks. The UFH is now only on at 2 stages per day in total about 5 hours. The Rads are probable on for 3 hours. I may experiment with running on the stats but I still do not have curtains and have a very open plan living area.
 
My plumber recommended that we keep our UFH on 24hours. Another customer of his took this advice. Similar house to ours ~3000sqft, similar insulation levels. The other customer uses 3+ tanks (1100L) of oil per year. We used 2 tanks last year, and since last fill September 07 we still have 1/3 a tank left. So looking like ~1.5 tanks for us this year. The difference? Well, our heat is on for 45mins downstairs only in the morning (06:15-07:00) and for under 3 hours in the evening (15:45-18:30) both downstairs and upstairs. I have to say I do not subscribe to this theory that if it's on 24hrs it will only call on the boiler when room temperature drops. Sounds so logical in theory. But with 13 stats able to call on the boiler in our house, it's as if there is almost always at least one calling on the boiler at any one time. Plus, you're potentially wasting energy keeping, for example, a sitting room warm from midnight until the following evening even though it's not used. Crazy. And in case someone suggests it, our house is occupied all day with little nippers, so has to be warm all day, and it is with this schedule of heating.
 
we are going to try running it for 3 hours a day and hopefully that will see a big improvment. Thanks for all the advice, really helpful
 
My plumber recommended that we keep our UFH on 24hours. ....... I have to say I do not subscribe to this theory that if it's on 24hrs it will only call on the boiler when room temperature drops. Sounds so logical in theory. But with 13 stats able to call on the boiler in our house, it's as if there is almost always at least one calling on the boiler at any one time. Plus, you're potentially wasting energy keeping, for example, a sitting room warm from midnight until the following evening even though it's not used. Crazy. And in case someone suggests it, our house is occupied all day with little nippers, so has to be warm all day, and it is with this schedule of heating.

Bobby, just as a general question, would you recommend UFH for all new builds or is it only of benefit for those (like yourself) who have family in the house during the day?
 
Have done searches but not finding answers in relation to this.
We moved in to our new house in june - had to refill the oil tank 2 weeks ago and we checked it at the weekend and its half gone already - it has used 450litres in 2 weeks!!

We have underfloor heating down stairs & rads upstairs. As we were off work over the hols the UFH was switched on from 9am - 11pm. Upstairs rads were only on for approx 2 hours a day.
PLEASE PLEASE PLEASE tell me this is not the norm for UFH. To me it means there must be a problem??? Any help or advise would be greatly appreciated on this.
 
Regardless of whether or not the house is occupied during the day, I would definitely recommend UFH. If ours was not occupied during the day, we'd simply eliminate the morning phase of heating. What I really like about UFH is the fact that the whole floor is heated up, and so after the "oil burning phase" is over, the entire floor acts like a big, slow release, storage heater. So compared to experience of houses with radiators (and well insulated ones at that) the heat lasts longer, especially for example in the bedrooms which maintain a comfortable heat all night. In any radiator heated house we had, we always had the upstairs heat coming on before we got up. In our current house, it's just downstairs that gets a small boost in the morning. Hope this helps.
 
I've been looking at all these posts in relation to the efficiency of UFH and I believe a lot of these systems are designed incorrectly. Most UFH heating is run directly off the oil boiler via a manifold. therefore when any circuit calls for heat the boiler has to come on. this results in the boiler continually cycling on and off in order to maintain the temp within each circuit which is very inefficient.
In order to run a UFH system correctly you need to run directly off a buffer tank. As UFH typically runs at 24C and the boiler output is typically 60C there will always be a mismatch. By running the UFH circuits directly off the buffer tank which has a large amount of water at approx 38C the boiler will only turn on when the stat on buffer tank drops below 38C which if you have a good insulated tank should not happen too often.
i will installing a buffer tank 500L in my own house later on this year. the buffer tank will be connected to a solar panel and also to the boiler so by combing the boiler and the solar panel my oil bill should be low. I will also have a step back function set on the room stats so that rooms such as the sitting room will only come on when needed in the evening time and other romms such as kitchen and living room will be on the whole time.
 
..... compared to experience of houses with radiators (and well insulated ones at that) the heat lasts longer, especially for example in the bedrooms which maintain a comfortable heat all night. In any radiator heated house we had, we always had the upstairs heat coming on before we got up. In our current house, it's just downstairs that gets a small boost in the morning. Hope this helps.

Yes the heat I'm sure would last longer... whether it's needed or not :-( Personally I don't like any heat in a bedroom at night. The radiator method provides heat when required and is off when not required which in it's own way is efficient also. I realise radiators mean the water must be heated to a higher temp and this is where it looses efficiency.

Anyway I still haven't made my mind up regarding UFH so thanks for your views on it... really helpful.
 
Hi Rahman,
Agree with you re. buffer tank. I have 500litre tank heated from oil and solid fuel. I have solar too but it heats the separate 300litre DHW cylinder since I'm not expected much solar heating of hot water in winter. Haven't moved in yet so can't talk about efficiency at this stage.
I was wondering how you chose the setting of 38C for your buffer tank by the way ?
 
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