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Indeed Richard, Gas->Liquid as opposed to Liquid-> Gas - I knew I should have just posted a diagram or a suitable link instead ?! eg. http://blog.autointhebox.com/what-you-dont-know-about-your-automotive-air-conditioning-system.html

  • Again I was simply trying to explain to JCMLuimini that the A/C system only has 'High' & 'Low' Sides by virtue of the (phase transition) nature of the refrigerant..... as opposed to Nitrogen and or a Vacuum (!)

JCMLuimini: Like Richard I don't know just how the system could apparently show different vacuum/N pressure characteristics between the High and Low sides either... unless, as he suggests. there is a blockage of some kind present...(?)

Now, referring to your original thread, ( in Oily Bits / https://rangerovers.pub/topic/3011-air-con and all your replacement parts ) it's bit of a long shot but (new) A/C components are often supplied with protective plastic plugs in the pipe ends / connectors etc of course (?)

  • That's 'a long shot' because you usually can not fit them without removing these plugs..... but 'it depends' (eg. I had a case - not P38 - where someone fitted a replacement ABS Modulator but did not notice some of the plastic stop plugs fitted for shipping etc were transparent rather than the usual red/yellow/etc. The requisite BSP connector inserted/tightened onto that missed plug thus produced both a blockage and a leak... but at least it was "obvious" !)

EDIT: I see you started (yet) another thread about this JCMLuimini and that your own leak was actually 'obvious' too ?!
PS: "You're welcome" !

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Gilbertd wrote:

davew wrote:

(The 'high pressure' side originates from the compressor (as gas) which reduces through the Condenser/fan as it cools (to liquid) but if there is a "divide" per se that could be considered the Expansion Valve... and it is then the Liquid/Gas transition in the Evaporator that produces the cooling - if that helps..).

Wrong way round. The compressor sucks in gas and it turns to liquid under pressure and gets hot in the condenser, which is why the condenser has cooling fans. The liquid then goes through the expansion valve where it boils, turns into a vapour and draws heat (to use the correct term) and gets cold. Same as using a lot out of a Calor gas cylinder when the liquid turns to a vapour and the cylinder gets cold, sometimes cold enough for condensation, if not ice, to form on the outside. The vapour passes through the evaporator (not strictly correct terminology as it evaporates at the expansion valve) drawing more heat from the surrounding air giving the the cold. That vapour then goes through the compressor and the cycle starts again. The low pressure side is where the refrigerant is a vapour and the high pressure side is where it is a liquid.

As to why one side will hold a vacuum and the other side won't, I've no idea as it is a closed circuit. If doing a pressure or vacuum test, it shouldn't matter which port you use because of that. The only time you can have problems is if there has been a leak in the past which someone has tried to fix with a leak sealer and it has sealed something that shouldn't be sealed. But if everything is new, that is pretty unlikely. The domestic systems I am installing only have one port which on the low side but as they are reversible to heat as well as cool (the compressor can reverse so the condenser becomes the evaporator and vice versa), when heating that port becomes the high side.

Ohh, is this like an Air Source heat pump that you can run in reverse? That sounds like a very nice thing to have.

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Exactly like an air source heat pump except rather than generating 55-60 degrees C and trying to use that to heat water to be pumped around radiators, it blows that out as hot air the same as a fan heater so has a much greater affect on room temperature. That is when it is heating of course, when cooling that hot air is blown outside and the cold side is in the house. I've just got in from installing one now. When doing the commissioning you run it first flat out cooling and check the interior and exterior temperatures, then do the same with it on maximum heating. When cooling I was getting air at 2.1 degrees being blown into the room and the outside unit was running at 26.8, only marginally above ambient. When on flat out heating the indoor unit was blowing air out at 61.3 degrees while the outdoor unit was down to 16.1. Not bad when you consider it was only drawing 550W of power to do that.

The other difference between AC and an air source heat pump is the Government will give you a grant and reduced VAT on an air source heat pump but bugger all on AC as the cooling aspect means you are getting a further benefit and not just replacing a perfectly adequate (and cheap) gas boiler with something horrendously expensive and not as good.

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Wow, colour me interested. I've got a really good five year old gas boiler which is ridiculously efficient, heats the house with tiny radiators and does instant hot water. The typical modern system. However, if I ever have to replace it we'll probably be unable to get a new gas boiler and Air Source will need new rads and a hot water cylinder. Pricey.
I'd rather rip the rads/piping out and put in your system - the house is insulated so much that a hairdryer will heat it quite adequately - and maybe do PV/Solar for hot water. Aircon would have been a distinct bonus last week!

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My phone was going bonkers last week with enquiries. The problem with new houses is they are so well insulated to keep the warm air in and not contribute to global warming, that as soon as we get a few days of warm weather bedrooms get ridiculously hot. I fitted a system in a new build, 3 storey, town house last week, one unit in the ground floor living room and one in each of the top floor bedrooms. Even when it was only 20 degrees outside it was up to 26 in the two bedrooms. The householder said it had got up to over 40 degrees in the bedrooms during the heatwave that they'd slept in the living room. Bugger of a job to do though as I had to hire a cherry picker as it was way too high to be able to work from a ladder or small scaffold tower.

During the winter I was installing systems for people so they could turn their radiators off and use the AC for heating instead as it is far cheaper to run, free if you have PV solar to supply the power. 2.5kW of heating for around 600W of electrical input, that's what you call efficient.

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We have a cellar, slept down there on an airbed for two nights in the heatwave.
14 deg down there, 32 in our bedroom extension built in 2001 with cavity insulation, rest of the house is 1903, bloody cold in winter, infact it's cold most of the year but I can't cope with heat so that suits me.

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Luckily, our insulation doesn't seem to have that effect during the heat. If we keep the curtains closed on the sunny side of the house it stays cool. I measured 23C in the hall (up from our standard 19C thermostat setting) when it was 36C outside - but if you open the windows you just let in warm air and that heat never leaves. I suspect that a very little power would heat/cool the house quickly, just as our gas boiler does now.
But... whatever happens I'll need to accumulate some capital first!

Edit - but if you go up in to the loft space - take a mop and bucket because you'll be melting in seconds! it's above the insulation layer so acts as a massive oven. The temps up there were unreal.

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Richard - a serious suggestion - and I know you are busy (and also on here too..) but how about starting a Thread or even a blog about all this.... ?

Background; I ask because so many folks seem interested in Heat Pumps but are clearly confused about the types and advantages etc.
-Nothing new in all that of course, Using PVC and then sell 'excess' power back to the grid (and dodgy providers as Ofgem did not regulate them properly... ); Similarly with the move from "Conventional" boilers to expensive Condensing types (not as reliable and not that 'better' overall either of course) and now many Heat Pump vendors abound (with multiple mistruths, like "only 10K guv" but not mentioning the much bigger rads needed and/or underfloor arrangements, plus the vital insulation improvements needed either. (This with a backdrop of 25% of our housing stock being solid wall too. Folks round here paying up to 20K to have rendered foam stuck on their walls). Whatever folks do/add/change 'Payback Periods' of 20 years or so are not uncommon !! Better stop there...

Anyhow, energy rip-offs rant over.. anyone else interested in this idea ?

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I may well do that when I get the time. I'm in Spain next week and nothing bores me more than sitting in the sun doing nothing so it would be a good opportunity.

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Yep, I'd be interested. Not because I think there's a great conspiracy but because there's a lack of real work experience talking to people about their options. The government seems happy to shout about insulation and banning gas boilers but there's a huge gap between those lofty goals and what is actually going to happen to our housing stock - very little of which was designed with heat pumps in mind.
I'm also very interested in Solar/PV but it's such a hot topic with the spamvertisers that I find it very hard to do any online research without triggering an avalanche of ads which just get in the way.
This actually sounds like a great idea for a new forum, tbh.

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How much does external temperature affect the efficiency?

Not saying this is the case... but if it were very efficient at heating a room from 20C to 25C when external temp is 20C but on the other hand far less efficient at heating a room when external temp is 5C it wouldn't be as real world efficient as the first set of numbers would suggest (nobody would even use a heater when external temp is 20C).

I've had a bit of experience with heat pumps used to heat radiators, in mild external temperatures no problem getting the radiators hot, in winter when you need them all the radiators just luke-warm. Probably due to the heat pump system not being big enough for the job of heating all the rads in cold external conditions though might have been big enough to heat one room?

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Depends on what you buy. I assume heat pumps are much the same but with AC systems some, usually cheapo Chinese ones, can't provide heat if the external temperature drops below -5C, so a bit pointless. Better quality ones, like the Fujitsu units I use, will still provide the normal amount of heat down to -15C. I installed a Panasonic branded system that the customer had sourced himself and the manual said that the difference between ambient and output should be greater than 8 degrees C, pretty poor by anyone's standards.

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Right, p38 picked up from the LR indy and after pressure testing the AC with nitrogen and dye, the condenser is leaking.
So I need another one. Looking on island 4x4 there is mention of having to use a different pipe on late 2001 models, mines November 2001, but sellers on ebay don't mention this.
Anybody shed some light on that?
Also recommendations for a manufacturer please. Should I also change the dryer and pressure switch for piece of mind before taking it back to have my work pressure tested and all being well- regassed.

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I'm tired , it's been a long day. But I've googled a bit and it seems the later ones are not available and pricey if you can find one. A work around involves some mods to mountings and a new hose or two, I'll have a better look tomorrow after some kip.

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The above is to fit the earlier and cheaper condenser to the later diesels BTW.

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Seems it's after VIN YA445076 that they changed, so if your VIN is before that it is part number STC3679 (which is the same as for the petrol models) but afterwards it is JRB000030. However, Island 4x4 say you can fit the earlier one if you change a hose and modify a bracket, see https://www.island-4x4.co.uk/condenser-9402-nissens-stc3679g-p-6871.html. Mind you, with the price of the pipe (https://www.island-4x4.co.uk/pipe-condenser-compressor-9400-awr5075-p-26888.html), it might be cheaper to get the more expensive correct one.

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Can't find the correct one in stock anywhere and the prices, even though they don't have any stock, is shocking to say the least, I've seen £1500 odd plus vat.
So it's the cheaper one plus the hose around £260 from island all in. Mahle brand at that price for the condenser, hose is genuine.
Bracket mod isn't as brutal as I thought, just a quick cut of two alloy brackets off the bottom of the engine cooler and maybe something knocked up to hold the bottom of the new longer condenser., not clear on that bit yet but it'll become clearer when it's in bits I'm sure.

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Forgot about this post. To update, to fit a taller earlier condensor to a later 38 diesel involves a new genuine (aftermarket not available) compressor to condenser hose and ,of course, a new condensor.
Trim a couple of alloy brackets off and in it goes. Grill slam panel and front bumper needs removing to fit the condenser, turbo to intercooler pipework needs removing to access the compressor pipe. All gassed up and working great.