Frequently Asked Questions

Floor Heating

What kind of a Boiler does Floor Heating Need?

Any boiler that will heat water will do; so gas, oil, even solid fuel will work. As floor heating only needs around 45ºC (I.E. only about the temperature of water in a bath), higher efficiencies can be also being attained from the use of condensing boilers and even more so with our Nibe heat pumps.

How Warm Does the Floor Surface Get?

A comfortable 27°C on average…not hot enough to notice unless you are walking in your bare feet…what could be more luxurious!

How difficult is Floor Heating to Install?

It's not difficult at all! The pipe is really easy to handle because of its metal core and it is simply laid out as per the AutoCAD drawings Unipipe provide. There are no joints to be made in the floor and the manifolds, which the pipes are connected to, are pre-assembled and just need fixing to the wall. Unipipe also provide schematic layouts showing interconnection to boilers, cylinders etc. to ensure compatibility.

Can our regular plumber fit it?

Yes of course! Also Unipipe can usually recommend an installer in your area and we provide on-site training.

Can We Mix Floor Heating and Radiators?

Yes, the control systems and design allow hotter water for radiators, towel rails, whilst cooler water flows to the floors.

Can You Control Each Room?

Yes, individual stats are usually placed in each room or area for this purpose. In setting up the system there is also control (by flow-meters) over the speed of water down each circuit to control floor temperatures over each circuit, so areas needing more heat such as conservatories can be catered for.

What Kind of Floor Coverings Can We Use?

Almost anything including stone, tiles, wood, (not thicker than ¾" or 22mm), Carpet (do not use a really thick underlay such as the old brown felt type).

Is Floor Heating Suitable for Old Buildings or Restorations?

Yes, if you are prepared to lift the floorboards or raise the floors in height a little. Floor heating will not only preserve the look of an old building, but quite often has a huge advantage over radiator heating, where there are high ceilings such as is typical in period buildings.

Geothermal / Ground-Source Heat Pump

What is the C.O.P. of a Heat Pump and what has it to do with Efficiency?

This stands for the Coefficient of Operating Performance…the higher this number is, the lower your running costs will be. Nibe's Geothermal range have reassuringly high C.O.P.s – most of our single phase range are 4.8 @ 0°/35° (some of our three phase units have the world record for type at 5.03).
I.E. for each Kilowatt of energy (E.S.B. unit) used in the motor of the heat pump, it will deliver 4.8kW of heat at 0°C from the collector and 35°C to the heating system. The 0°/35° figures are a benchmark for a point of performance, just like when a motor dealer quotes the M.P.G. of a car at a constant 55MPH instead of what it might use going downhill at 30 with a tailwind!
In Ireland, with our mild climate, it is usual with a properly dimensioned collector or borehole to see an average of about 7°C or more in the collector fluid in winter, with much higher temperatures again in summer. At 7°/ 35°, the COP of a Nibe 1120 or 1220 ground-source heat pump is 5.75 to 1….at 7°/50° it drops off to 4.0 to 1…still not bad though with many heat pumps just having COPs of just 3 to 1. The lesson here is that the warmer the water your heating system will need, naturally enough, the higher your bills will be. Also the warmer you can get the collector fluid (or Brine as we call it) to the heat pump, the higher will be its COP, and the lower the running costs.

Which Size Heat Pump do we Need?

A good rule of thumb is to work on around 50 watts per square meter for an average home, so for example a 200m2 house will need 10kW (10,000watts) of heat. The ideal machine for this is a NIBE 8kW heat pump; remember its rated output is 8kW at the European benchmark of 0°/35°, but in Ireland with our higher ground temperatures, its output is just over 10kW and the perfect match for the above example.
Do not be tempted to oversize a heat pump installation no matter what well meaning advice you may get from your plumber, builder etc. An oversized heat pump will cost more to run, but worse still will not last as long because of the higher frequency of unnecessary starts and stops.

Borehole or Surface Collector?

The site of your project will usually determine this… if you are building a new home and perhaps have yet to landscape, surface loops of 40mm plastic pipe would be the most likely choice. They are placed in trenches about a meter deep and about a meter apart to collect the earth's heat. If your site is very tight for space, or rocky, or the job is a retrofit you will use a borehole. Unipipe (Irl) Ltd will provide the depth of borehole dimensions for you. If you can't use a borehole, then you might consider using an Air-to-Water or Aerothermal heat pump!

What's in the Borehole or Energy Well?

There is a one-piece U-bend of 40mm plastic made by Uponor Energiesysteme, at the end of which is a concrete pilot weight to facilitate dropping the collector. Inside the well piping is a mixture of 33% Ethylene Glycol (anti-freeze) and water referred to as Brine. This is circulated by the heat pump and energy extracted from it and turned into high grade heat for your house, hot water swimming pool etc.
The boreholes are not lined all the way down, just the very top part through the top soil till the driller hits rock. The pipes are in water in the well, which when cooled, takes heat continuously from the surrounding rock. You may have more than one borehole in a bigger house or commercial property, and the boreholes should be at least 12m apart from each other.

Which Heat Pump - We have three types!

Ground Source (Geothermal)
Lowest possible running costs, even at very low outdoor temperatures. They are ideal for large buildings and new-builds. A ground collector will be required or a borehole, so some outdoor room will be needed. Lake Water can be used also. All-In-One machines including hot water (1220 Range) are available which greatly cuts down on installation time of both the heating and plumbing job. Larger heat pumps are available in this range for bigger building - largest single phase unit is 12kW Output (@ 0°/35°) Three phase units available up to 40kW output – Also up to nine units may be docked together giving 360kW.

Air to Water (Aerothermal)
Ideal for retrofits, city homes or if boreholes are not possible. Minimum interference during installation. Can collect heat from air down to –7°C Usually fitted with some back-up system which automatically takes over in very low temperatures – this can be electric as this really happens very few hours in the heating season. Still very low running costs in the mild Irish climate; overall heating bill just about 10% higher than ground source Can be docked to existing gas or oil systems.

Exhaust-Air Heatpumps
Primarily used in Air-Tight, low energy homes where correct ventilation is vitally important. For apartment developments and homes up to 180m2 All in one solution for heating, Hot water and heat recovery ventilation – faster installation time, no outdoor work. Not for use in older homes or very large dwellings Ideal with special construction systems and used in Kingspan Dryform, Century, Viking and Huf-Haus Homes amongst many others.

Heat Pumps

How deep is a typical Borehole?

A 200m2 property with an 8kW heat pump will usually have a 150M deep energy well. A 12kW heat pump for a 300m2 house will need 180 to 220 M depth, which could be two 110 deep holes.

Can I use our Ordinary Water well?

No! It won't be deep enough, we could freeze the water in it, and the submersible water pump could damage the collector pipes just to name a few of the reasons!

Can we use any type of Hot Water Cylinder?

No, you must use a NIBE VPA type cylinder with its specially dimensioned accumulator in its outer jacket, or else use a 1240 model heat pump with integrated cylinder.

May we integrate Solar heating to the heat pump system?

Yes, we have a few different ways of doing this; please consult us for further design help to ensure good results.

How Much Electricity Does The Heat Pump Use?

Annual energy use will vary of course from home to home given different insulation values, air-tightness of building and preferences of occupants. A 12kW Nibe 1240, heating a 300m2 home will use just under 3kW whilst heating a floor heating system, but will be delivering around 15kW of heat.
The official figures – According to test data standard ENN255, Brine in 7°C and heating out at 35°C, 2.6kW used by the compressor and 14.98kW to the heating system, resulting in a C.O.P. of 5.75. Typically you can expect a 70% saving on traditional heating methods such as oil.

Should we get a Night-Rate E.S.B. Meter?

Yes, as electricity is less than half-price during the night, so unless you are in a very small property it would be mad not to! Also as our machines are linked to the weather outside, and it is usually colder at night, they naturally 'farm in' heat at the cheaper rate when it's most needed. Also, if you have floor heating in concrete, you can take further advantage of storing heat in the floors which can last all through the day with the heat pump at rest.
If the building is an office or school for example, and you have floor heating in a heavy concrete slab of 150mm or so, you may never need to use the more expensive day rate at all.

Why do Heatpumps not need a buffer tank?

The intelligent control systems in our heatpumps require the compressor to dun hot only for the relatively short periods for domestic water heating (usually set to stop at 55 degrees) Once this task is completed, the control take into consideration the outside temperature via a small sensor outdoors and the temperature produced by the machine will match the building needs. No energy is wasted and al all time we minimize the amount of heat created.
So on a day where the temperature outside is for example 5 degrees, the heatpump will deliver just 30 degrees to the floor heating, giving a very high C.O.P. If the weather cools to minus 1 degree, that temperature will automatically increase to about 38 degrees. The varying temperature output is referred to as Floating condensing Technology. When the outside temperature is sufficiently high the machine shuts down production of heat and run only to replenish domestic hot water.
If we used a buffer tank, we would have to make higher temperature, have a lower C.O.P and higher running costs. Not to mention extra equipment extra cost and extra space to house them.

Life Expectancy and Servicing

We are told that the expected lifespan of our Heatpumps compressor is around 80,000 hours. We see an annual average of 2500 – 3000 hours of running times on most of our customers’ machine. This then should give an expected lifespan of 27 years, by which time the machine will have saved its owner many times the installation cost.

Will our hot water be hot enough?

Any of our machines will heat your domestic hot water to about 55 degrees or even a little more if required. However one can only tolerate 38 degrees on the skin! The cylinders we use are generally larger than those in ordinary heating systems which may be at 60 degrees or so. A popular cylinder we use is a 300/200 – this has 300 liters of water in it surrounded by an outer jacket of 200 liters of heating water. Our heatpumps also can raise this temperature by immersions or built in electric boilers: this is automatically done every ten days on most types to prevent the occurrence of Legionella.