burning lots of oil any suggestions to ease the pain

rosnacanee

Have just finished building a 2800 sqft story and a half. We have used 700 euro worth of oil since the end of august. We had the heating on all the time for three weeks to get the house slowly heated up but since then it has only been on 4 hours a day. 5-7 in the am, 5-7 in the pm.

We have underfloor heating downstairs and rads upstairs running on a 90/120 gerkros boiler - 20,000btu. plumber assures me that it has been comissioned and balanced and suits the house perfectly.

The main living areas are set at 20degrees. I have the thermostat set to come on and off at the same time as the boiler.

the house is well insulated 5 inches in the floor, 80mm xtratherm in the 120 cavity, all attic sealed with a mixture of paper and cellulose, all external walls have 38mm insulated slab, triple glazed windows.

We like heat but even still I find the amoun of money spent on oil excessive, seriously regretting installing the underfloor think rads might suit us better.

Could anyone offer any suggestion or something i might be doing wrong. Maybe this sounds right and i just have alot of space to heat.

Thanks

MicktheMan

rosnacanee wrote: »

Have just finished building a 2800 sqft story and a half. We have used 700 euro worth of oil since the end of august. We had the heating on all the time for three weeks to get the house slowly heated up but since then it has only been on 4 hours a day. 5-7 in the am, 5-7 in the pm.

We have underfloor heating downstairs and rads upstairs running on a 90/120 gerkros boiler - 20,000btu. plumber assures me that it has been comissioned and balanced and suits the house perfectly.

The main living areas are set at 20degrees. I have the thermostat set to come on and off at the same time as the boiler.

the house is well insulated 5 inches in the floor, 80mm xtratherm in the 120 cavity, all attic sealed with a mixture of paper and cellulose, all external walls have 38mm insulated slab, triple glazed windows.

We like heat but even still I find the amoun of money spent on oil excessive, seriously regretting installing the underfloor think rads might suit us better.

Could anyone offer any suggestion or something i might be doing wrong. Maybe this sounds right and i just have alot of space to heat.

Thanks

Your house is still drying out and as a result more energy is needed to get it to desired temperature. You may find that next year when your house is fully dry your oil consumption will be dramatically reduced.

Having said that, uf heating is a low temperature slow thermal response system and is not well suited to short on/off periods. Remember the floor slab is being heated not just the water. On the other hand, rads are a fast response high temperature system and are well suited to short on/off periods.

I'm assuming that the boiler heats a buffer tank and the u/f is fed from this. How exactly are the boiler/uf/rads controlled? Maybe you should ask the person who designed the system how best to optimise the control/use of the system. Imo, the whole system needs to be fully understood in order to get the best out of it.

mrgaa1

I'm not being funny here but have you considered putting on another layer of clothes - instead of a t-shirt around the house perhaps a t-shirt with hoody?

Also is there anyone who is in the house all-day? If so your body adjusts to the surrounding temperature and then you can feel cold whilst someone coming in will certainly feel the heat.

On your RADS upstairs are there TRV's on them - and in rooms that are not used is the TRV turned down.

You have a big house - are the internal doors in your house kept closed?
Your vents for your bathrooms - are they sealed?

Do any of your neighbours use the same fuel supplier? Have they noticed any changes in fuel consumption?
Its giving it to get a lot colder over the next week or so.

mickdw

Id say your boiler is running at max output for those 4 hours as I doubt the underfloor would be getting the temp up to thermostat set levels in that time.

Id try going the other way - allow the boiler to run most of the time, set your thermostats at the low side of comfortable for the living areas and depending on your system, turn sleeping areas off during daytime.
This will put little demand on the heat pac and you would most likely find that it runs for a minute or so every so often just to maintain room temperatures. The boiler will then also not have a warm up stage.
Certainly having underfloor, you have little option but to run it in this manner.

aidanic

Underfloor heating takes an age (1-2 days) to come up to temperature, after which it requires very little energy to keep it going. I get the feeling you're treating the underfloor like radiators, and they are not the same.

I'd suggest that you ensure water temperature in the pipes in the underfloor is in the 30-40 degrees range, and not 60-70 which is normal for wall radiators. Then run the system, on all the time, for a few days with the room termostats set to 20 degrees. If the floor sides are insulated correctly, you'll have to bring the entire concrete floor up to 20 degrees, and this could take 1-2 days. Then all you need to do is add enough energy to cover the heat losses into the building (i.e. keeping you warm).

Allowing the slab to cool down for 20 hours per day and heating it for just four is not wise. You've be better off with radiators for this kind of regiem, and heat the air. Any heat added to the floor during the warming periods is quickly lost, and the boiler is working very hard when it does come on to bring the slab back up to some temperature.

We have underfloor, and making a small change requires 1-2 days for it to come through. It's taken most of a year to get used to it from radiators.

Think of steering an oil tanker at sea rather than some natty little italian sports car

rosnacanee

Boiler doesn’t heat a buffer tank, the boiler is in the garage and I have a 300L tank in the hot press inside. I have one of those non heat loss insulated pipes coming across the yard so the heat isn’t lost there.

The rads are zoned upatairs in three zones and are controlled by a dial thermostat linked to a valve in the hotpress. The underfloor is controlled by Heatmiser stats in each room downstairs.

Doors are closed most of the time, two bathrooms are stil waiting for the vent cover but I don’t think its gonna have that much of an effect
Aidanic think you are right. We have lived for the last ten years with rads so might try leaving the boiler on and using the stats on the wall to control the heating rather than the timer for the boiler.

Hope it works. Thanks a million for all your help

bbam

Hi..
Sorry to hear your bother but that is a serious oil bill, our house is the same size and also 1.5 story but we have rads, we got a fill of oil last April and have used about 250litres since, the room stat consistantly reads 18-19 degrees with no oil on and we only have oil on for 40 minutes a day limited to 21degrees.
Have also used about €200 of sticks in a solid fuel stove.

Did you take sufficient measures for airtightness during the build, insulation and airtightness go hand in hand to provide an economic comfortable home...
An example would be the 80mm insulation in the cavity is great but would be seriously compromised if it were fitted with gaps no matter how small... Cold bridges on wall ties and other detailing are of vital importance.. the inside leaf of blockwork should be plastered before dry lining to prevent air infiltration.

Definitly change the running of the system to allow the underfloor heat sufficiently, if this doesn't work I'd be chasing down draughts no matter how small and pumping the remainder of that great big cavity..

Poor Uncle Tom

rosnacanee wrote: »

I have one of those non heat loss insulated pipes coming across the yard so the heat isn’t lost there.

There is no such a thing, the heat loss may be small but there will still be a heat loss. What distance is there from the boiler to the house?

Is there any breeze getting to any of the stats themselves?

This might seem like a silly question but how is your house ventilated? Are there open fireplaces? Are the windows fully sealed from the cavities? The wiring conduets, are they sealed?

rosnacanee

Thanks again lads,

the distance from the house to the garage is about ten metres. I have taken good airtightness mesaures i feel. I use window vents for ventilation. All other holes gaps etc are filled to the best of my knowledge spent all summer going around checking all these things. There is definetly no breeze in the house and we have two stoves so no open fire. we sealed the window cavities with the xtratherm cavity closer aswell. Thought i was gona burn very little oil with all these measures.

The house is by no means cold i'm just worried about the quantity of oil been burned.

I'm after changing over the timer on the boiler to always on now, I presume the stats will control when it needs to be on or off. Also should i Have the on temp lower higher or the same as the off temperature??

BryanF

a house takes at least 6 months to dry out, and you are also getting used to the house and the heating systems, experiment! as suggested above and check room temps to see how accurate your heat controls are. (also taking surface temperatures can give you some interesting results) especially on non -certified windows and in areas you haven't been able to control workmanship.

how deep is the boiler pipe buried?
have you tested your TRV's?
is there a chance your losing heat from rooms your rarely in? ie can you reduce your bills by trning off certain zones.

the heating does seem excessive, the dry-lining is reducing your thermal mass so this may explain (in-part) why the use of rads is not keeping the house warm for long periods.

if this doesn't improve after xmas (when you've probably been heating it more continuously, consider thermal imagery test and air-tightness.

rosnacanee

Back again!!!

Have tried numerous things, it still seems to be burning a high amount of oil. The plumber is really uncreative as regards to solutions.

He now thinks that i need an extra boiler, one for the rads and hot water and one for the underfloor. To test if this works he said to turn the thermostat down to the last on the boiler and it will giv an indication if the new boiler will work.

I used the stove to back up the hot water as when the boiler is turned down it doesnt heat it up to the required temp.

After i did this it made no difference as the oil is being consumed at the same rate. Its costing me about 300 euro a month.

I have the sitting room, hall, back hall turned down to 13 degrees which it never even comes near to. The other rooms, the kitchen, sunroom and bedroom are at 20 degrees, all upstairs rads are off.

I haven't a clue where the problem is, wud the electrical work be wrong, a jet in the burner,

Is there any person i.e. an engineer who could come to the house and evaluate the whole systema nd see if there is anything up,

Thanks for all the help but its recking my head at the moment and also recking my pocket

bbam

To be honest I can't see how a 20,000btu boiler would be enough? But I also know there are calculations to work this out..
We have a rad setup in a similar house and our burner is 120,000btu and our stove is 100,000btu. I'd wonder if the burner isn't flat out most of the time or maybe it has an incorrect jet installed.

I was warned off oil running underfloor by a few folks who said it was expensive to run but that's no good to you now...

rosnacanee

Sorry it is actually 120000 btu

MicktheMan

rosnacanee wrote: »

We have underfloor heating downstairs and rads upstairs running on a 90/120 gerkros boiler - 20,000btu. plumber assures me that it has been comissioned and balanced and suits the house perfectly.

rosnacanee wrote: »

Back again!!!

The plumber is really uncreative as regards to solutions.

He now thinks that i need an extra boiler, one for the rads and hot water and one for the underfloor.

Does your plumber know what he is doing ... looks like he is contradicting himself!

You mentioned earlier that your external walls have insulated slabs. Were these applied onto bare block walls? If so, then this is a large airtightness weakness in the house as concrete blocks are porous and not airtight.
Did you have the house tested for airtightness? If so, what was the result? If not, why not? Airtightness, imo, may be key to your high heating bills but will also help inform on optimum ventilation strategy.

How well was the cavity wall insulation fitted to the inner leaf and to each other?
How exactly is the ceiling/roof insulated?

Your 120k btu boiler should be well capable of supplying the house with sufficient heat assuming that the building fabric is constructed correctly (wrt airtightness / insulation / thermal bridge detail etc). Changing the boiler or adding an extra one won't solve the house losing heat - remember, the reason for a heating system in the first place is not to heat a house but to replace the heat lost through the building fabric.

tred

My thoughts on this, is what a poster has said above. There are many many posts here about using an oil burner to heat underfloor. you have to heat up the whole downfloor mass to achieve your 20 degrees. underfloor doesnt give you instant heat like rads. So your boiler is working harder and longer to get that underfloor going. Have you a secondary heat source like a stove in the main room???

PaleRider

I believe the amount of energy you are using is about right. Did you get a BER for the desgin. Going by your description, your house could be a B2 Rating. If that the case then you would need approx three fills of oil per year for heating and DHW.

I don,t think your house is at fault. I do agree with the notion that the screeded floor needs more time to heat up.

If your house was Professionally Designed the amount of energy to heat the house may be recorded, and if so check with Person responsible.

Be careful about floor coverings on the UFH Screed as heavy or unsuitable coverings can restict heat flow.

Also if your site is on high exposed ground, this will add to your heat bill.

You have recived some sound advice on the other posts, which would be very wise to follow.

A few ideas

1. Try to switch of heating to rooms not in use.
2. If you have access to chimney, would you consider a wood stove for the living area.
3. Try and better understand the heating controls.

Try not to worry about this, i think you done everything right. Enjoy your new home.
Check out SEAI Web Site for more ideas on saving energy.