Sweco Aerothermal heat pumps...

billy_beckham

Any one out there found the best and most efficient way to run one of these aereothermal heat pumps. I have just installed a unit from Sweco. It uses 2kw to run the heat pump but also has three 3kw elements which can kick in depending on the temp in the 500l tank.The heat output of the unit is 10.5kw.

We have UFH downstairs and rad's upstairs. Each of the zone's downstairs are controlled by room stats which open/close valves on the manifold. At the moment i have a time clock on the pumps for both the ufh and the rad's.I have been playing with different setting's on the clock ie running ufh pump at night to heat floor slab and just having it come only for half hour stint's during the day to keep the slab topped up, that way trying to run heat pump on the cheaper night rate esb.
I saw a few posts on site before about these units and was wondering how other people ran there heatings systems, any advice would be apppreciated..............

patrido

the ideal way to run it on night rate leccy is to use a biggish very well insulated thermal store instead of a hot water cylinder. you heat up the store during the night, and then set the zone timers for when you actually need the heating on.

you also get the benefit of mains pressure hot water in showers and taps.

though as you've got your system already installed, you might not want to go to this hassle.

billy_beckham

The system has a 500l thermal store....also i think with the ufh you need to keep the slab temp constant

patrido

ok, nice one

regards keeping the slab temp constant, this is true an extent, but you don't have to keep it at normal room temp all the time. at night time and times when the house is unoccupied, i would recommend having a setback temperature, where the room/slab temp is about 7 degrees less than normal occupied temperature. this is much more efficient that either having it on all the time or letting it fall back to ambient.

to get everything working efficiently, i would start by getting the ufh delivering heat to the rooms you want, when and only when you need it. the rest of the time you really need setback, and if you don't have a thermostat/controller capable of that, i would look into retrofitting them. they shouldn't be very expensive and should save a fortune.

when you are happy with the ufh timings/temps, i would start experimenting with how long to have the heat pump on for during the night, and how early to set it going.

who did you buy the thermal store from? i would be surprised if they were not able to help you with this as many thermal stores are connected to heat pumps and often another heat source.

i'm interested to hear your opinion on the store... was it an off the shelf model, or custom made? one of those fancy square ones? expensive?

billy_beckham

I have a thermostatic mixing valve on the supply to the UFH manifold with has a clock, setback feature's etc. So it can take care of lowering the temp at night, just on that what is the recommended temp of the supply water to the UFH about 30oC?...Also what should you be looking for in your room's about 17oC? Any advice would be great!

The heat pump unit i bought from Sweco come's with the pump, the evaporator(outside unit) and the 500l thermal store so i don't know exactly how much it cost.

patrido

billy_beckham wrote:

I have a thermostatic mixing valve on the supply to the UFH manifold with has a clock, setback feature's etc. So it can take care of lowering the temp at night, just on that what is the recommended temp of the supply water to the UFH about 30oC?...Also what should you be looking for in your room's about 17oC? Any advice would be great!

The heat pump unit i bought from Sweco come's with the pump, the evaporator(outside unit) and the 500l thermal store so i don't know exactly how much it cost.

room temperature is traditionally thought to be 20 degrees - in passive rooms (where you are sitting, watching tv, etc) 20 degrees should be comfortable. kitchens (not dining), hallways and bedrooms can be a tad lower, bathrooms generally a degree or two higher. it's really down to personal preference though. start at 20 and adjust for comfort - slowly, a degree at a time, and give it a few hours to adjust.

in order to heat a room to 20 degrees, the floor surface can reach temps of up to around 30 degrees (29 degrees in normal rooms, 33 degrees in bathrooms are the normal upper limits defined by BS 1264).

to reach these surface temperatures the water temp will need to be a lot higher than 30 degrees. you should have been provided with a detailed spec for the ufh detailing the design temperature for the ufh circuit.
it really depends on the heatloss for each room, the pipe diameter, pipe spacing, flow rates, etc, but i would expect it to be more like 45 or even 50 degrees. however, I wouldn't just crank it up to 50 straight away... if the supplier cannot give you the design water temperature, you'll have to experiment yourself.

basically, you need to find the water temperature that will allow the coldest room in the house to maintain comfortable room temperature, when it is cold outside (at or close to freezing point). you'll need to use an accurate thermometer for the room, located away from draughts, sunlight and other heat sources. always make small adjustments - one degree at a time, and give it a few hours to react. if you have to go much above 50 i'd get further advice. it might be fine, but you need to be sure. if you have wooden floors anywhere, you need to be very careful that the screed surface temp does not exceed 29 degrees.

WILKEL

billy_beckham wrote:

Any one out there found the best and most efficient way to run one of these aereothermal heat pumps. I have just installed a unit from Sweco. It uses 2kw to run the heat pump but also has three 3kw elements which can kick in depending on the temp in the 500l tank.The heat output of the unit is 10.5kw.

We have UFH downstairs and rad's upstairs. Each of the zone's downstairs are controlled by room stats which open/close valves on the manifold. At the moment i have a time clock on the pumps for both the ufh and the rad's.I have been playing with different setting's on the clock ie running ufh pump at night to heat floor slab and just having it come only for half hour stint's during the day to keep the slab topped up, that way trying to run heat pump on the cheaper night rate esb.
I saw a few posts on site before about these units and was wondering how other people ran there heatings systems, any advice would be apppreciated..............

I am no help to you on this but might consider one in the future - you must have high electric costs running this unit. What kind of ESB bill are you getting.
Sorry for going slightly off topic.

yop

Billy just to clarify the output you were told from this pump is 10.5kw of heat for every KW of electric??

Also you would have been looking at about 12k euro for that setup. Similar to what they quoted me.

billy_beckham

Here is the info from there website Yop, the model we have is the sweco 11..
So for 2kw in it gives out 10.5 of heat


Heatpump model Sweco 7 Air Sweco 11 Air Sweco 22 Air
Evaporation method Air Air Air
Power Input at 0/35* 1,3kW 2,0 kW 4,0 kW
Heating output at 0/35* 7,1 kW 10,5kW 21 kW
Heatfactor(COP) at 0/35* 5,3 5,3 5,3
Voltage 230V 230V 230V
Refrigerant R-407C R-407C R-407C
Condensor tank 500 l 500 l 500 l