Venting a portable air conditioner

I feel problem with "portable" air-con is that its shooting itself in the foot. It heats air and expels it, but what replaces the expelled air. Usually more hot air, so yes its cooler than that you expelled, but presumably hotter than you want. You also have the compressor in the room with you so noisy.

Probably ok but see above...

No I can't see this being usefull

these are not intended to be permanent so I doubt any one has done it

you probably would not get a a decent air flow...

... The normal way to use these is to vent through a window.....

Much cheaper to run. Can heat as well as cool. Do not take up floor space. Install one for heating purposes. I think you need to ask your local authority the rules seem unclear.....

Dave

Several suppliers seem to imply no planning for a single unit needed...

You should find this more informative than the US website:

I bought a Honeywell HC09CESAWK portable a/c in June last year, and have been very pleased with it (it's only been used once this "summer" unfortunately! Next week looks more likely, however). Although it's rated at "only" 9000BTU, it can easily cool our 24m^2 lounge (actually

It's also much better than our old a/c unit (which lost its gas and couldn't be refilled) as the condensed water doesn't have to be emptied

- it is expelled with the hot air through the vent.

The hot air is expelled through a casement window. To do this I cut a piece of 4mm twin-walled polycarbonate to exactly the maximum size of the casement frame - 1200 x 570mm. A hole to take the 150mm exhaust hose was cut low down and a vent bolted onto the polycarbonate sheet. To fit the sheet to the PVC window frame I used several pieces of self-adhesive velcro. This works well and holds the sheet on firmly. The casement window is opened fairly widely so the airflow isn't obstructed in any way. It's easy to pull the sheet away from the window when we've finished with the a/c. Obviously it's a security hazard when being used, but it's on a side window almost 20m from the road, and well hidden by shrubs.

It means keeping the chimney open, which allows more air exchanges, and lower effectiveness of the air con.

No, it sounds like a dumb idea unless you also install a duct in the void and connect to an extenal vent (which to be fair is what many US HVAC installers do - a flexible insulated duct)

Not for air con, but core drilling through a wall is not usually that difficult - done it plenty of times for soil pipes, air vents, boiler flues etc.

Could work... again I would use a duct.

Probably not - since you can get a split unit heat pump aircon for a few hundred these days.

"Class G also has a curious condition: "the air source heat pump shall be used solely for heating purposes". I do not know what this means, but perhaps "heating purposes", means changing the temperature inside a building rather than exporting heat through pipes to the neighbourhood. I cannot believe the heat pump is allowed to run one way but not the other."

This was the condition I was referring to. In recent(ish) discussions I have seen it suggested that this means that you don't need permission if you are heating radiators, hot water, etc. but you do if you are just cooling a room. Although an air source heat pump with an internal fan unit can both heat and cool a room. There is a possibility that this is aimed at replacing gas boilers but not using extra electricity to cool a house down.

I doubt there is any enforcement unless a neighbour complains a great deal.

However it is a strangely worded condition.

Cheers

Dave R

The 'I' in this text is Richard Gawler who wrote most of that page. I wouldn't put any store by what he does or doesn't believe.

(I think he is wrong in his suggestion about what heating purposes means)

AIUI this is to do with replacement of gas boilers, with several conflicting wishes:

- the government doesn't want to encourage air conditioning because that would cause extra electricity demand, which might end up burning gas to meet and putting more pressure on the grid

- the government does want to encourage the replacement of gas boilers with heat pumps

- the government, through its various grant schemes, doesn't want to fund the installation of air conditioning units. This was previously more strongly enforced than it now is (ie cooling-capable units couldn't be installed, now they can).

- the government is concerned that outdoor units will create noise. Boilers already create noise (especially outdoor mounted ones, which is common for oil), so running a heat pump for heating doesn't necessarily increase that. Lots of air conditioners running together in a heatwave is extra noise.

which results in the kind of mixed messaging behind this rule.

If the unit is installed for wet heating, you can't really tell the difference between running it to make a supply of hot water (maybe a whole series of people having baths) and running for cooling, unless it's running for long periods.

Theo

Whilst I am sure many of you will disagree, I would say we are cutting our nose off to spite our face, or really that the government does not want to admit to some basic truths. If average temperatures continue to rise and the population continues to age we need to be planning for and deploying cooling capable air conditioning systems.

The NHS admits that older people are more susceptible:-

.. so lots will need AC to survive and surely its most needed in sunny weather so solar can take up some of the stress, perhaps instead of not cooking tea at 5pm we will have to shut down our AC when the sun isn't shining...

.. but perhaps this push against AC is really because they want to kill a few of us off....

Dave

I agree, there's a massive blindspot about overheating. Building design really hasn't considered solar gain, with the result that new builds are nicely insulated but warm up like greenhouses in the summer and there's nowhere for the heat to go.

However it would be better to deal with this via passive measures: thermal mass, shading, window coverings, ventilation, fans. Those cost (next to) nothing to run and minimal to no electricity demand. Aircon should only be the last resort when all else has failed - the ideal should be that building design makes the place habitable for most of the year and you only need aircon for a week or two.

We're just so completely clueless and unprepared.

Theo

I think we are getting beyond the point where passive measures are effective. Whilst my Spanish house has lots of thermal mass, with walls that are about 18"/90cm think, and a rear wall that is cut into the solid rock of the hill behind me and small, shuttered windows my wife hates so she opens the windows and shutters and turns the aircon on...

I don't see how you can get my English house with single brick walls and large windows anything like as cool....

So we agree on one thing...

Dave

It's not exactly tropical here. I live in the South of England, in a house without cavity walls, no A/C or even evaporation coolers and the highest interior temperature we have reached is 26 degrees C. Warmer than comfortable, but not dangerously high. We do have ceiling fans in most rooms, which may be non-U but do help.

We reached 32 last week in the 'office' upstairs. It is a large room but has a fair amount of equipment in it. Last year I think it got to 35.

Air conditioning does two things. Temperature and humidity. It condenses water out of the air, and the drain line has to go somewhere. My drain line goes into the sump pit, and there is enough water condensed, that occasionally the sump pump, pumps it to the outside of the house.

Humidity control, allows you to take the heat during the day, without turning the airconditioning on. You can have solar gain during the day, and mostly stand it until 5:00-5:30PM in the afternoon. The cheap electricity is available at 7PM.

You try not to dump too much moisture into the air during the day, then one long run on the AC at night, brings the humidity back to about 40%.

AC is much more practical, if your house is designed for it. Using split-units to aircon here, that would double the price of implementation. A central air unit is a lot cheaper than using a bunch of splits.

A typical air conditioner run here, lasts for five or six hours. Then it is off until the next day, for another five or six hour run. Not many people run their AC like this, but I do.

When the air conditioner was new, its capacity was too high for the size of household. But when the thing is low on gas (modern ones are always low on gas), then the cooling rate is less, and the machine does a better job of dehumidifying until the target temperature is reached. The brand new AC could hit the target temperature in three hours (clammy feeling air), versus the six hour run now (dry air). The first year, was three hour runs. Years after that (even after a gas refill), have been six hours.

The policy in the southern united states, is two central air units minimum, and some houses have three central air units. If one central air unit fails and needs maintenance, the family temporarily moves into the half of the house that is still cool. That is an example of what the future holds. That design will become more common as time passes (this would be on a house you would consider to be a McMansion).

Maybe in that case, splits are more attractive, but then you would have more of them than in a UK application. There would be so many splits, it would be hard to keep track of the maintenance condition of each (which one that is low or close to empty, on R gas). When you're low on gas, the A-coil freezes up and becomes a solid block of ice. And that can damage the fins on it. You don't want to call for a refill, prematurely, but you also don't want to cause the machine to leak. The machines usually have rudimentary protection against pathological states. Expensive ones, have readouts.

And while you can achieve some thermal control, via the usage of earthen berms on three sides of a house, there is still humidity control to consider and how you will dry the air, even if the temperature is decent. The central air above, happens to solve two problems at once, and the humidity aspect should not be ignored. A lot of your comfort comes from proper humidity.

Paul

Then you would be a fool!

I know Richard personally - a very highly skilled systems engineer and technical author - a detail man to the core!

He rarely commits anything to paper without careful research first.

I read that to mean heating a room rather than cooling a room - which is my understanding of the situation. What's yours?

I'm at that point - considering replacing an aged and failing gas combi (as per recent posts). But from the quotes I've had, it's not making sense yet. £15,000 for the ASHP and a water store - so £7500 cost to me after the grant. That's not including insulation and resizings radiators.

OOI, does anyone know the costs of ASHP design and installation labour? I did a quick estimate from what I could glean from the quote's parts list and it came to about £11,000. Which /seems/ a lot . . .

As you say - it's complex. Anecdotally, I'd say the noise at a gas flue is far lower than the noise at an ASHP going full pelt, and ASHP tend to run a lot longer - not far off 24/7 during heating.

It would be good if the government would publish its thinking on this whole cooling/heating situation.

So long as it's installed according to regs, I think the complainant is wasting their time complaining.

Which an ASHP does - much longer than its gas equivalent.

That may be, but I would not take the above as planning advice. If you want to understand what a specific part of planning law says, ask somebody with knowledge of planning law (eg your local authority, who are ultimately the enforcers in your local area). "I cannot believe the law saying X could possibly mean X" is not a good basis for making planning decisions.

Theo

I read that 'heating purposes' means 'heating purposes', not 'heating the rest of the village' or 'changing the temperature negatively inside a building'. ie an ASHP for heating your house is fine, an ASHP for cooling requires planning permission. IANA planning lawyer, ask somebody more clueful than me.

It seems to vary quite a bit depending on the current value of the grants...

Octopus claim they have it down to parity with a gas boiler with the £7.5k grant, ie let say it costs you £1-2k, they get £7.5k grant, so the total cost is £8.5-9.5k. I don't know what circumstances that's quoted for.

I think they have a high temperature heat pump so they avoid having to upgrade radiators at some loss of efficiency, and they have a number of other ways they're streamlined the process (eg bulk deals with HP manufacturers).

If you don't have an existing hot water cylinder it might be more to install one, especially if you need a loft mounted cylinder because there's no space for it downstairs.

Labour is probably ballpark a week for minimum two people (the kit is big and heavy), perhaps plus an electrician if they aren't qualified for that.

Not really. The ASHP is sized to run at full pelt during the coldest winter day. Most days aren't as cold, so it'll either modulate (spin less enthusiastically, down to some limit) or below that it'll cycle (run periodically, eg once an hour or few), depending on the heating loads required. Those are much less noisy.

Agreed, I think we need a cooling strategy. Building regs cover overheating, but that's only for new builds. Most of the things there don't apply to existing properties.

I suppose one option is to do it anyway, and then make a retrospective application if anyone complains.

It doesn't, most of the time for heating. It's only running at full tilt for hot water (where you might have a whole tank to heat from cold if somebody drained it with a bath), or cooling where it's trying to fight major continuous heat sources (solar gain, or eg Bob's computer room, where there's say an N kW continuous heating load that it has to work against). If the loads are small the noise is much less.

Theo

Nothing wrong with taking professional / paid for advice, or for that matter checking if references in a wiki document are still correct some years after it was last updated etc.

I suspect that the planning doc linked to in:

However it does seem to be the legislation cited by many air con installation companies, since there does not appear to be any more relevant (domestic) legislation that applies.

Building regs generally don't kick in for domestic installs unless you can't comply with the location / size limits specified in G1 of [1].

My comment however was mainly directed at what read like a rather dismissive attitude to a detailed a well written article, where the author went to some obvious effort to include links to the relevant information.

I think there's some conflation of building regs and planning permission going on here.

Building regs says that when you build or modify buildings they have to be to certain standards.

Modifications require planning permission unless they are covered by permitted development.

As your G1 cite above indicates, ASHPs are permitted development if they are "used solely for heating purposes". Perhaps a gas boiler replacement is, but an air conditioner is unlikely to be 'used solely for heating purposes'.

This is about usage rather than capability, which complicates things a bit. You can install an ASHP that's capable of cooling and heating, and only use it for heating without needing PP. If you want it for cooling then you need to apply for PP.

Therefore a conclusion that's plausible to draw is that planning permission is required. Drawing the conclusion that really 'cooling = heating' and what requires PP is district heating is a bit of a stretch.

A third set of rules applied to the old RHI grants: it wasn't possible to install anything with cooling capability even if it was never used. The result was that some ASHPs had a secret jumper that was used to disable cooling for the UK market. Remove the jumper and magically cooling works. Those rules don't apply any more, so AIUI grant-funded ASHPs can have cooling functionality although likely the grant wouldn't pay for installation of features that aren't to do with heating. According to the logic above they would still need PP to run them in cooling mode.

So there are several overlapping sets of rules: building regs, planning permission, permitted development and any grant scheme rules. It's important to understand which rules are being referred.

Needing PP shouldn't be the end of the world if the situation isn't controversial, although it does cost a bit in fees and time. PD is a shortcut but not everything is eligible for the shortcut.

However IANA a planning lawyer and so you should ask somebody who isn't me for planning advice.

I was purely being critical of what appeared to be wishful thinking, and also to address the rather odd way the article is worded (lots in the first person but no author byline - I had to look at the edit history to make a guess who 'I' was).

Theo

They are separate things, but both may require permission or one form or another.

However things that are permitted development, don't require explicit PP.

As I said the focus of the document is not really air con.

You could draw the conclusion. Personally I would not at least not for small domestic systems that meet the not too large / near / in conservation area etc requirements.

This is the position that seems to be taken by all the HVAC contractors that discuss the issue on their web sites etc.

ok fairy snuff.

Well there are plenty of "here is how I did it" style articles on the wiki - I know because I have written a few! While I take care to try and not write misleading things, that are intended for inspiration, encouragement, and entertainment rather than just being a dry reference.