Any Home A/C engineers? Advice needed please

Discussion in 'OT (OFF Topic) Forums' started by reflexboy, Jul 16, 2011.

  1. reflexboy

    reflexboy MB Enthusiast

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    I have a small bedroom (11ftx10ft) and in the summer it's like a sauna. I was thinking of installing a split AC unit to help me sleep. Are these 'DIY', pre-gassed systems any good? Surely the length of connecting pipe between the units won't have any gas in them and therefore the system will be short of gas from day one? Am I missing the point or do they self bleed?
    The bedroom is on the first floor at the front, with a loft above, so I was thinking of mounting the wall unit at ceiling level and then running the pipework into the loft, and then out of the soffit board at the rear of the house and wall mounting the external unit. Would this work and are these pre-gassed, DIY jobbies any good? I have a portable AC unit that I vent out thru the wall and it's too noisy to sleep with it on and not that cold. Thanks in advance chaps.

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  2. st13phil

    st13phil MB Enthusiast

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    I'm not an a/c engineer but we had a/c installed in two upstairs rooms four years ago and did a fair deal of research back then before settling on getting a local installer to do the job.

    One thing that puzzles me about the DIY installations is how you evacuate the pipework which is absolutely critical to the system working properly and reliably? As far as gassing the system goes, most (all?) split systems are supplied pre-gassed and unless you have a particularly short or particularly long pipe run the gas quantity is OK. If you do need to adjust the gas level you'd need to get someone with the right kit to do it though.

    We chose a multi-split system with enough capacity to run three (or four, depending on capacity) indoor units even though we only installed two. The rationale is that if you do decide to expand the system it's relatively inexpensive to do so as you only have to install another internal unit and pipe it up. We also chose to use an inverter system which varies the speed of the compressor according to cooling or heating load and is much more efficient in use than a (cheaper) non-inverter system which has to stop and start to maintain the desired room temperature.

    Your description of pipe routing is pretty similar to ours, except our installer ran the pipework through the wall and then up through the soffit, across the loft space and down through the soffit on the other side of the house to the compressor. Don't forget that you need to run a condensate drain too and unless you want to install a pumped drain that needs to exit downwards. Our compressor is bolted to the ground at the side of the house but wall mounting fairly high up is advisable if you're in many areas as pikey's will quite happily cut the cables and pipework to nick a compressor unit for its scrap value. Finally, you need a pretty heavy-duty power supply for the compressor unit and as it's sited outside it has to be armoured cable with an external isolator.

    We found that professional instalation was cheaper than we thought and, frankly, you know that you're going to get a proper job done and that if a fault develops then they'll fix it. As a guide, our install took a guy working on his own three days to do from start to finish. It'd take a lot longer to do if you're learning on the job.
     
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  3. OP
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    reflexboy

    reflexboy MB Enthusiast

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    Thanks for your reply Phil. As it is only a small room, and only one room I wanted to 'cool', I was rather hoping this could be a DIY project.
     
  4. st13phil

    st13phil MB Enthusiast

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    Sorry, I wasn't saying "don't DIY" (and in fact that may be perfectly feasible), I was just trying to give a little more insight into some of the potential pitfalls :thumb:

    There are a couple of other things I forgot to mention earlier. The rooms we installed the units in are south-facing and the windows are above the roof of a single story extension so they get really hot in the summer months - typically up to 30c if it's been a sunny day. One room (approx 9ft x 9ft) is used as an office while the other is a bedroom and is about 12ft x 14ft. On the installer's advice we fitted 9,000btu internal units and the capacity certainly seems to be about right. Regarding siting the indoor unit we had no choice in our bedroom but to put it on the wall above the head of the bed but this is not really ideal from a draught point of view, and we have to select the airflow direction with care. If you have a choice of possible locations and can get it away from the bed head then my advice would be to do so. Also, as you're looking to cool a bedroom then make sure that the internal unit has a "quiet" or "night time" mode that reduces the fan speed otherwise it will keep you awake just like your portable unit.

    Out of curiosity, have you approached any professional installers to get a quote? As well as giving you a price, they'll also be able to suggest the best solution for your needs so even if you do finally decide to go down the DIY route you'll have better information about the cooling capacity you need and so forth.

    Although our system only gets used for a relatively short period in the summer I'd say it's been worth every penny. Arriving at work in the morning refreshed after a good night's sleep in a cool room and hearing exhausted colleagues moaning about getting no sleep when it's hot is a reminder of how much difference it makes to your life :D
     
  5. John

    John Hardcore MB Enthusiast

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    I maybe wrong here but I'd heard the law had changed and it was now not legal for DIY aircon installs. Might be worth ensuring you are still allowed to do it yourself?
     
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  6. John

    John Hardcore MB Enthusiast

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    Might just be certain types of installation then:

    "In the UK it is ILLEGAL to self-install systems where you bend your own copper pipe and fill them with refrigerent simply by opening service valves on the units and bleeding the air to atmosphere.Venting of refrigerent gases to the atmosphere is illegal. Open pipe systems BY LAW have to be installed by an approved refrigeration contractor (the equivalent of CORGI Gas approval) using specialised equipment that evacuates the pipework and then charges the system using self contained gas exchange units. Our sealed umbilical systems do not vent gas in any way and are therefore quite safe and legal to install yourself. "
     
  7. OP
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    reflexboy

    reflexboy MB Enthusiast

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    Interesting points there guys. As Phil says, perhaps a local installer could help me here, even if i don't accept his quote.
     

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