Enormous Electricity Bills from underfloor heating

traumatised

Hi i was just wondering if anyone had knowledge about ESB bills in relation to Underfloor heating. I seem to be getting bills that i consider ridiculous and am nearly bankrupt from (not Kidding)! My electric bills seem to average at about 800 euros every two months! I have an underfloor heating system which is operated off an air to water boiler thing. i was lead to believe that this would be economical and cost effective not insanely expensive and causing sleepless night! we also have a well that i guess the pump operates off electricity as well and a bio waste water tank too. Is this kind of money the norm does anyone know? :eek::eek::eek:
I'd appreciate anyone's expertise on this matter as i'm withered from it:mad:

M cebee

don't know much but you could prob monitor your usage with an owl monitor to get an idea whats happening
Do you have the ufh system setup optimally-temperatures,timing and dual tarriff metering if needed

Bruthal

If an air to water heat exchanger is used to heat the water for underfloor heating, it will be going day and night. Massive amounts of air would have to be moved across the exchanger evaporator, and even more so the colder the air is.

I would of thought they would only be viable for heating the hot water cylinder, and even then, they would probably struggle in cold weather, even with the exchanger in the attic.

2011

Let me qualify my post by stating that I am no expert on air source heat pumps and I have never installed one. I have however installed a ground source heat pump which is a kind of first cousin

First of all it is always good to have a basic understanding how this type of system works.

This short video is very informative. Although it is for a ground source heat pump, the principle of operation for the air source heat pump is the same.

It is often said that these systems work like a "fridge backwards". A fridge removes heat from the interior by emitting it out the back. These units remove some heat from the air outside and transfer it into the house.

As ambient air temperatures are higher during the day I would think that these units will work more efficiently during the day. This is just my opinion, so it would be best to ask this question to the installer directly.

Although with a dual tariff metering system (day & night metering system) the off peak (night rate) electricity is cheaper I would think that this will not time that your air source heat pump should be running. Dual tariff metering as well as having a higher standing charge also charge more per unit during peak times. Therefore I would think that unlike a ground source heat pump a single tariff meter would be best.

It is always best to have the rooms in the house split into different zones. By turning off a zones in rooms that do not require heat savings can be made.

Each zone should have its own thermostat. By turning down the stats further savings can be made. This also applies to the domestic hot water (water used for showers, bath, washing hands etc..). This should be on its own zone with its own stat and own timer.

I would also think that the air source heat pump should only be running for a few hours per day at most at this time of year as it should only be heating domestic hot water. I can heat my hot water with my €30 immersion for a cost per month far below €800

During the winter it should be running more, but not to the point that monthly bills are €800.

If this was my system I would install an Owl energy meter on it. That way I could monitor exactly how much it is costing me at any given time for small money.

A few questions to the OP:

1) How big is the house?

2) How much of the time is the unit running for per day?

3) What are the electrical ratings of the unit in terms of kW input? This should be written on the unit (or ask the installer).

4) Do you have a dual tariff meter installed?

5) Have you talked to the installer about the issues you are having?
6) How may zones and stats are installed?

7) Is there a stat installed on your hot water tank?

8) Is your home well insulated?

9) Are the windows closed when you have the heating on?

10) Are the underfloor zones switched off during the summer?

11) What sort of time clock(s) are installed to control this system?

12) Has the operation of the system been clearly explained to you?

Bruthal

The problem with air source ones is the low density of air. Huge volumes of air required to heat water which is 800 times as dense.

It is possible for air at 20 degrees as an example to heat water to 70 or 80 degrees or to boiling. But the bigger the difference in temperature, the more volume of air that must pass over the evaporator.

It is sort of like how a bath of cold water would have more heat in it than a red hot bolt. As the evaporator refrigerant goes into the evaporator and drops in pressure, it boils (-20 or so at atmospheric pressure), absorbing heat from the surrounding medium, air in this case. Then into compressor, compressed into liquid in the condensor, and releases the heat picked up in the evaporator.

An air source one would be running a lot anyway, and the colder it is out (when its needed the most), the more it will run, for the same output.

Outkast_IRE

I have said it before on here and i will say it again , nobody has any business with and air to water heat pump , unless
They have an incredibly well insulated home, i wold be tempted to say a passiv home , thats very airtight.


Quick question OP ? does the Air to water heat pump , heat the hot water in the hot water cylinder, This can abosolutly send the bills through the roof.

Also what temp is it set to , there is always the possibility it was sized incorrectly.

Last summer OP i took one of these out of a house thats only 3 years old, they got an oil boiler instead and have never been happier.

2011

Outkast_IRE wrote: »

I have said it before on here and i will say it again , nobody has any business with and air to water heat pump , unless
They have an incredibly well insulated home, i wold be tempted to say a passiv home , thats very airtight.

For all we know the OP has an extremely well insulated home. That is what I asked the question in my previous post.

A few simple tweaks may be all that is required. I think it would be best to have a bit more information to hand before condemning the entire installation.

liveandnetural

its all in here the good the bad and the ugly

http://www.boards.ie/vbulletin/showthread.php?t=2055433218

maddragon

An incorrectly commissioned heat pump can easily lead to the types of bills the OP describes. The well use should be minimal but check to make sure the ballcock in the attic isn't stuck which could lead to a constant stream of water out the overflow. I found this problem in my own house with an energy monitor similar to the owl. The usage kept going from a base load of 200 watts to 1.5 kW every so often. I knew it was probably the well pump and sure enough at the back of the house I could hear the flow of water coming out of the attic into the downpipe. Went into the attic and found the ballcock had stuck. Remember 1kW per hour will add up to €135 or so per month. My own knowledge of air to water heat pumps is limited but my understanding is that they would not be expected to provide your heating requirements when the temp drops below about minus 5 and get progressively less efficient as you approach that temp.

Some very useful advice above. Mine is to get the current system checked by a reputable expert and if it has been commissioned correctly and assuming your house is well insulated and reasonably airtight then take out the heat pump and replace it with a ground source heat pump or a condensing oil boiler.

meercat

also check that you are on dual tariff metering too

Bruthal

2011 wrote: »

For all we know the OP has an extremely well insulated home. That is what I asked the question in my previous post.

A few simple tweaks may be all that is required. I think it would be best to have a bit more information to hand before condemning the entire installation.

There simply wont be the same output from an air source, as a ground source heat pump, particularly in cool or cold weather.

2011

robbie7730 wrote: »

There simply wont be the same output from an air source, as a ground source heat pump, particularly in cool or cold weather.

I never suggested that an air source heat pump was as efficient as a ground source heat pump, besides right now the weather in not very cold. I am simply suggesting that it may be possible for the OP's system to run more efficiently than it is.

If an air source heat pump is thought to be responsible for pushing the ESB bills to €800 then the facts should be investigated first before jumping to conclusions.

Right now we have no idea of the size of the house, how much of the time the unit is switched on for, what other electrical loads there are, if the bills are estimated, if the heating has been on full blast deliberately to dry out new plaster.

Bruthal

2011 wrote: »

I never suggested that an air source heat pump was as efficient as a ground source heat pump, besides right now the weather in not very cold. I am simply suggesting that it may be possible for the OP's system to run more efficiently than it is.

If an air source heat pump is thought to be responsible for pushing the ESB bills to €800 then the facts should be investigated first before jumping to conclusions.

Right now we have no idea of the size of the house, how much of the time the unit is switched on for, what other electrical loads there are, if the bills are estimated, if the heating has been on full blast deliberately to dry out new plaster.

Its opinions I post, as always. Not cures.

traumatised

THANKS VERY MUCH FOR ALL YER SUGGESTIONS AND COMMENTS I APPRECIATE IT FOR SURE. I HAVE A LOT TO LOOK INTO BUT I CAN TELL YOU THAT THE LAST BILL WAS WHILE THE UNDERFLOOR HEATING WAS OFF AND WE THOUGHT IT WAS AN ESTIMATE FROM THE PREVIOUS BILL BUT APPARENTLY NOT! THE HOUSE IS ABOUT 3000 SQUARE FEET AND IT IS ZONED AND THERE ARE THERMOSTATS WHICH ARE USUALLY AT 20 DEGREES. THERE IS BASICALLY A BUFFER TANK IN OUR GARAGE AND THIS IS WHAT IS HEATED APPARENTLY AND THEN TRANSFERRED INTO THE HOUSE FROM THAT. i'LL ADMIT YES I AM FEMALE SO I REALLY AM NOT GOOD AT THIS TECHNICAL TALK AT ALL SO MY APOLOGIES. I KNOW THE HOUSE IS EXTREMELY WELL INSULATED THAT IS ASSURED. THE GUY THAT INSTALLED IT HAD A GOOD REP BUT DOESN'T TAKE ANY CALLS OR RETURN THEM SO THATS UPSETTING. WE DO HAVE A DUAL SYSTEM IE THERE IS ALSO AN OIL TANK BUT IT HASN'T BEEN WORKING SINCE THE GUY INSTALLED IT. HE DID COME BACK TWICE AND SAID HE FIXED IT BUT STILL DIDN'T WORK, WE ALSO HAD A FRIEND LOOK AT IT WHOSE A PLUMBER AND HE COULDN'T FIGURE OUT THE PROBLEM SO THAT'S WHY WE'RE KINDA STUCK AT THE MOMENT. I WILL LOOK INTO THIS OWL METER YE MENTIONED

Bruthal

As others have said, the heating, and well pump would be the two items worth looking into.

The fact the air source system requires almost air tight houses to work at all in a financially viable way, would suggest that if a house was that well insulated, then a condensing oil boiler would seem likely to be as good or better, in such a well insulated house.

2011

robbie7730 wrote: »

As others have said, the heating, and well pump would be the two items worth looking into.

Perhaps I am missing something fundamental here due to my lack of experience with air source heat pumps.
My question is what well pump?
I know that there is a well pump on a vertical collector ground source heat pump, because I was invalid in installing one. But I can't see here there is one on an air source heat pump.

Bruthal

2011 wrote: »

Perhaps I am missing something fundamental here due to my lack of experience with air source heat pumps.
My question is what well pump?
I know that there is a well pump on a vertical collector ground source heat pump, because I was invalid in installing one. But I can't see here there is one on an air source heat pump.

There is none associated with an air source refrigeration circuit alright.

But the OP has a water well and pump i believe.

The diagram in your post is a split AC unit by the look of it. For heating one room, and while they are air source, they are also heating air direct, so not as big a temp differential is needed between evaporator and condensor, as when heating water.

The reversing valve just swaps the condensor with the evaporator, for cooling the room in hot weather.

The same reducing efficiency happens as when the evaporator is out in cold air trying to extract heat from it for heating the room, but now the condensor is outside in hot weather trying to get rid of the heat collected in the evaporator when cooling the room.

2011

traumatised wrote: »

THE LAST BILL WAS WHILE THE UNDERFLOOR HEATING WAS OFF AND WE THOUGHT IT WAS AN ESTIMATE FROM THE PREVIOUS BILL BUT APPARENTLY NOT!

If the underfloor heating was off this is what should have happened:
1) Heat pump switches on via time clock.

2) The heat pump circulates hot water though a coil in the hot water cylinder. This in turn heats the water that will flow out of your taps.

3) After a reasonable amount of time the temperature of the water in the cylinder reaches the temperature set point on the cylinder stat. The stat is now "satisfied". A normal set point for domestic hot water would be 60 Deg C.

4) As the hot water in the cylinder is now at 60 Deg C the heat pump is no longer required so it automatically switches off. This I suspect is not the case with yours. The circulation pumps on many of these systems will run for a little bit longer, know as "pump overrun".

5) All of the zone valves for the underfloor heating system should remain closed all during the entire operation. None of the underfloor zones should be "calling" for the heat pump. Again I would think that this may not be the case with your system.

6) If the heat pump runs for more than 3 hours to heat a cylinder of water you may find that it is cheaper to simply turn off the unit altogether and use the immersion or boiler. It might be a case that an air source heat pump can never get the domestic hot water to the set point of the stat (assuming that there is a stat).

How long is the timer on the heat pump set for per day? Are you sure that it turns off when it should?
Typically is their a large demand for hot water in your home? How many baths / showers per day normally?

THE HOUSE IS ABOUT 3000 SQUARE FEET AND IT IS ZONED AND THERE ARE THERMOSTATS WHICH ARE USUALLY AT 20 DEGREES.

I would suggest that you turn these thermostats down to their lowest setting until you require the underfloor heating to come on again. It is possible that the rooms are at say 16 Deg C and the heat pump is trying to heat them to 20 Deg C. As the weather is not cold you may have exterior doors and windows open much of the time. These units and underfloor heating in particular are not designed to heat a home quickly.

THERE IS BASICALLY A BUFFER TANK IN OUR GARAGE AND THIS IS WHAT IS HEATED APPARENTLY AND THEN TRANSFERRED INTO THE HOUSE FROM THAT.

Is the garage a separate building? If so are the pipes well insulated between the buffer tank and the house? This might be something worth looking at as I have seen significant hate loss in this way before.

i'LL ADMIT YES I AM FEMALE SO I REALLY AM NOT GOOD AT THIS TECHNICAL TALK AT ALL SO MY APOLOGIES

I am working with some very talented female engineers with considerable technical expertise so I would not dare to make any disparaging remarks :D

I KNOW THE HOUSE IS EXTREMELY WELL INSULATED THAT IS ASSURED

That is good news.
Do you have any idea what energy rating the house has? Do you have a BER certificate ?

THE GUY THAT INSTALLED IT HAD A GOOD REP BUT DOESN'T TAKE ANY CALLS OR RETURN THEM SO THATS UPSETTING.

If it were me and the friendly approach failed I would give him an ultimatum and then perhaps reluctantly threaten legal action.

WE DO HAVE A DUAL SYSTEM IE THERE IS ALSO AN OIL TANK BUT IT HASN'T BEEN WORKING SINCE THE GUY INSTALLED IT.

The same guy? Oil burners are generally very reliable. Are you sure about his reputation being good?

traumatised

Just to clarify the well pump is indeed for a water well and i also mentioned a pump for the waste water reason being i believe these are run off electricity also and wondering if these are driving the bill up. thanks again for all the suggestions i will investigate further

2011

robbie7730 wrote: »

There is none associated with an air source refrigeration circuit alright.

Thanks, I thought I was really missing something

2011

traumatised wrote: »

Just to clarify the well pump is indeed for a water well and i also mentioned a pump for the waste water reason being i believe these are run off electricity also and wondering if these are driving the bill up. thanks again for all the suggestions i will investigate further

I think that you should get the Owl energy monitor that was referred to earlier. Install this on each device that you suspect you may be responsible for your large bills for a few days. You may need some assistance with that.

Once you have positively identified the device(s) that are primarily responsible for the large bills then you know what to target. Perhaps your large bills are the result of a number of devices running for long periods when they are not required.

traumatised

thanks again for all the helpful suggestions i'm going to get the owl meter and will ley ye know how it goes

deandean

OP I was in a house with electric u/floor heating a while back, the owner was complaining of huge ESB bills but OMG the house was like a bleedin' sauna! I could see where the energy was going.

Try turn your thermostats right down. 18Deg, except perhaps for the main lovingroom which could be 19Deg or 20deg. Bedrooms, 16Deg. Heating OFF in zones when not needed.

The idea of keeping your entire house at 20Deg is gonna cost you.

traumatised

Well we defo don't have a sauan agoing on that's for sure it is generally at 17-18 degrees in the bedrooms and then as you said 20 degrees in the living area but like it has been turned off since april and the last bill for may june was still 800 so that's just bizzare:eek:

marknjb

on the water pump just check that the pressure tank is ok and not water logged as this can drive up a bill a large amount as the pump is cutting in and out every time a dribble of water is let off

arse..biscuits

€800 for a 2 month bill is crazy. What part of the country are you in? I have an energy meter which you can borrow if you're near me (Firhouse, Dublin)

MortgageBroker

Anybody know a heat pump troubleshooter? I'm getting bills of 800e which are way higher than everybody else seems to get using a heat pump - only company I called didn't get back to me