# portable heater very large room



## indebtedgal (2 Jan 2011)

i hope this hasnt been done before but i need some advice urgently. we have moved into a new house and the living/kitchen area is really big with under floor heating and we ust cant keep it warm and its drinking oil so i need to get an efficient heater to supplement this, i was thinking a superser.. what are the pros and cons or do i have other options, i have a little oil filled rad at the moment(electric) and its not a drop in the ocean so to speak..


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## esox (2 Jan 2011)

IMO your looking at this in problem from the wrong angle, i think you should if you haven't already try to increase the output of the ufheating in that room your plumber or supplier will be able to do this. uf =heating can be on the heavy side with oil consumption but if you are running even an 'efficient' heater the average size of this should be round 2-3kw for a large kitchen/dining room and i think this would more than double the cost of heating the room with your oil fired boiler.

maybe you should take a look at the boiler itself, upgrade to a high-efficiency model also to make sure the boiler is sized correctly for the job ie kw output of boiler matches the kw input needed for heating and domestic hot water.

i see alot of boilers over sized for the job which all leads to inefficiencies in the system.


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## indebtedgal (4 Jan 2011)

there is now talk of changing a jet in the boiler, does anyone know what effect this would have if any on fuel consumption...


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## Shane007 (4 Jan 2011)

Changing the jet along with changing the oil pump pressure will increase the power of the boiler. This will use more oil, in the region of 0.15 US Gallons per hour. You can only increase this as per manufacturer's instructions. Most boilers only have 3 nozzle sizes/power outputs, i.e. low, mid and high, such as in a 70/90 boiler, you can have 70,000 Btu, 80,000 Btu or 90,000 Btu. This will not increase the temperature of the water travelling through your floor as it is mixed down from approx 70C to between 25 and 35C at the manifold. You would only increase the output of the boiler if the total demand is not being met by the boiler.
Before you do that, calculate the heat losses of the room, compare that to the output of the underfloor heating circuit for that room. If could be that the losses are outwaying the heat from the circuit. Calulate the loss and deliberately assume that the installer did not insulate around the external perimeter of the room (below the concrete). This can be a conserable loss.
Calculate the following, assuming Living Room Design Room Temp = 21C and outside Design Temp = -3C:
Temp Difference = 24.
Ventilation Heat Loss = 2 air changes per hour
Length of room (m) x width (m) x height (m) x 2 (air changes) = m3/hour x 0.33 x 24 = Heat Loss for ventilation in Watts. (Add this to end total)
Fabric Heat Loss:
Floor Length x Width = Area x 0.79 x 24 = Heat Loss in Watts (Add this to end total)
External Wall Length x Height - (Glazing & External doors) x 0.68 x 24 = Watts (Add to total)
Glazing Width x Height = Area x 2.8 x 24 = Watts (Add to total)
External Doors Width x Height = Area x 2.8 x 24 = Watts (Add to total)
Ceiling/Roof Length x Width = Area x 1.41 x 24 = Watts (Add to total)
Add all totals.
Add 10% if walls are exposed such as northfacing.
Add 10% if unusually high ceilings.
Add 15% if room is only intermittently heated.
Add these to your previous total.
Divide this total by 0.709 for an emission factor and this will give you a the total demand required from the heating circuit. Compare this to the output of the circuit. If the amount is much higher, you will need to either lower the demand, i.e. insulate external walls, improve u-value of window/door, ceiling etc. or increase the output of the circuit, but not so easy with underfloor. 
If above too complicated, PM me with dimensions, wall type, etc. and I will calculate for you.


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## mcaul (11 Jan 2011)

I've just bought 2 x lucht 1.8kw heaters for a 1000 sq  ft showroom and after a week of use find them excellent. - Both are on castors.

They use electricity for 20 - 30 mins each hour yet give heat out for the full hour. I won't know  how big the savings are - but previously I was using a 3kw over door heater and a 2kw blow heater to make it comfortable.

If it works the way I have worked it out, they'll pay for themselves within a year. [broken link removed]


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