Anyone done anything like whole house DIY-ish air con ? For example, air con unit in loft (meaty one), vents in roof, DIY ducting around house, to air condition the main rooms of the house. It strikes me this might be easier than those through-the-wall units in one or two rooms. Bung a duct down unused chimney breast etc. Might need booster pumps due to large ducting lengths. Any thoughts ? Simon.
Might be less work to use a multi-unit split aircon - small pipes instead of big ducts. I'm pretty sure you can get systems with one outdoor unit to run multiple indoor ones.
Also, think about all the places you could get condensation if you're blowing cold air through ducting (like on the outside of all the ducts, unless well insulated).
I'd recommend the Xpelair or Olympia range of air conditioners:
It also means that should a unit fail you only loose air conditioning in that room only. If you have a system with one centralised unit when that fails you loose cooling for the whole house.
If you ever tried getting an air conditioning engineer out in the height of summer you'll know what an advantage this is!
I have installed one of these systems so far and they are *really* effective. Installation takes less than an hour-drill two 6" holes, fix the aircon unit to the wall, plug in and away you go!
sponix
No, one day soon, awaiting round tuits.
Depends what you mean by "air con".
AC as seen in cars and as delivered by Hitachi split system cassettes should be more correctly called comfort cooling. Proper AC controls not only temperature, but also humidity and cleanliness of the air. Mr Carrier developed AC to control humidity, not temperature. Go google for more info.
If you want cooling, and something akin to a conventional AC system chucking out an icy cold gale, I don't think this is practical. The duct work needs to be insulated and have a vapour barrier.
Fans. I'd suggest you'd need some advice before starting.
IMHO, you can live comfortably without AC in the UK unlike, say, the US deep south or tropics. It is insidious in that, once you become accustomed to it in the car or at work, you then start to feel uncomfortable without it.
If your main aim was warm, clean air & ,possibly, a bit of ccooling, it is more promising. 'Which' did an investigation of energy savings (I think, I've been told of this but never seen the report) many years back & found that whole house ventilation was a major labour saving device. If the house is supplied with filtered air at a slight positive pressure, then the ingress of draughts and airborne dirt is greatly reduced. Routine cleaning is reduced accordingly. You could use a displacement ventilation system (Google) since these use low velocity supply air at a smaller differential temperature; this could be operated to avoid condensation on the ducts, but the ducts should still be thermally insulated.
Thesw systems are more common in the US, mainly due to more disposable income I think. Google for "Lifebreath".
Expensive and noisy. The compressor is indoors, and the heat exchange to outdoors appears to be via an air duct, thus adding to the cooling needs. The Cop is very low, 2.3, I'd expect well over 3 for a modern system, otherwise you are paying through the nose whilst using it.
Why? There is no need for a/c in the UK if:
- insulation is added (cavity wall, 300mm in the loft)
- the place made more air-tight
- adequate shading in summer (awnings, shutters, deciduous trees, etc)
- adequate ventilation, taking in cooler air from the north side.
- ect
a./c "costs" to run maintain. What you could do is the above points and add a heat recovery and vent system. But the house must be pretty air tight, otherwise you are venting twice.
We just don't have the climate for a/c. In other countries no matter what you do they will need a/c. We just don't have those climates and a cool building can be had by using a variety of other means.
The difficulty with ducting is that it would need to be two way. Air con is not just about pumping cold air into the room. You also need to extract the warm moist air since it is the dehumidification that makes a big difference to the comfort level and not just the temperature.
Getting two sets of insulated ducting to/from each room is going to be harder.
A split system that uses several internal air handlers connected to a single external condensor would be a simpler job to install.
I did look into options for doing this (when I had the roof off the house seemed like the ideal opportunity!) but could not find any multi way split systems that were avaiable for self install (one or two way units were available - but four way seemed more elusive). The "professional" installation often cost more than the hardware costs by a fair margin! (i.e. an internal heat pump air handler costing 250 quid say, was often accompanied by an installation charge of 500!). There also seemed to be a certain amount of "closed shop" mentality going on as well, in that many suppliers were not keen to supply the kit to people outside of the HVAC funny handshake club.
US systems feed into each room, but have a smaller number of common return ducts, typically from the hallways, kitchen, and bathroom. Actually, I don't recall any feeds into the kitchens and bathrooms either -- probably just keep these at negative pressure to avoid heat, moisture, and smells invading rest of house.
When I looked at these systems for an office, admittedly some 8 years ago, the multiple evaporator systems could only have a single thermostat. That made them fine for very large rooms, but not for multiple rooms. Things maybe different with them nowadays.
I don't know where the crossover point is, but multiple internal units are more commonly done with fan coil units running from chilled and heated water circuits. A single outdoor chiller is used to create the chilled water to drive them (and sometimes the heated water too, particularly for buildings which need some parts cooling and other parts heating at the same time).
The ones I saw would let you have different stat temps for each air handler. The only thing you could not run, was a combination of air con and heat pump at the same time.
I found quite a few split units that worked with conventional refrigerant circulation (and water outlet) that went up to 4 way with a single condensor. More than four and there were also some cascaded condensor arrangements.
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