twin outlet aircon, separate pipes or common plenum?

[vas]

hello all,

trying to tidy up things and reclaim some storage space where I relocated the aircon due to the stab fitting. So this is the reverse cycle thing which features two individual fans off the same matrix (That's how I see it at least!) leading to two 125mm dia pipes:

for what it's worth it's a CLIMMA Split 24 MK3 (that's 24k btu)

and it's now under the lower helm floor with the pipework coming at a handy hatch next to the helm seat and at the moment taking most of the space for no reason.
Pump lives below next to the stbrd fin stab.

Next pic shows the preffered layout of the pipework (OK too generous in space, could well be much more compact and squashed to the right of the pic):

so top of pic is the .5m long 100mm dia hose to the stbrd cabin
mid and from the left the newish pipe is the 2.5m to the port cabin
to the bottom of the pic is the one going to the salon sofa area with a smallish tee off to a 75mm dia to the galley (combined lengths 3.5m)
just to the bottom barely visible is an oval 100mm dia outlet to the steps to the salon

Bow cabin gets a big round hatch by the anchor winch and gets free fresh air, so no air con there. Besides routing a 100mm pipe all the way there would be a bit of a nightmare tbh...

Obviously the two bigger 125mm pipes to the right are the aircon outlets.

enough with the facts, quick Q:

i'm about to fabricate two plastic or mildsteel plenums on a local fabricator.
Should I do ONE large instead with both inlets and all four outlets out of it?
Don't want the whole thing vibrating and being noisy, nor restricting flow, but sizewise and shapewise, I'm sure I can manage.

Makes sense, or crap idea?


cheers

V.

 

[Portofino]

View attachment 75152

For the benefit ( I hope ? ) of others -
Tbo Vas is it really that “ split “ in the sense of the distance from the compressor circled in red to the air handler circled in blue .If I have understood your pic ?

You need to max out on the outlets so four is better then three and two etc - assuming you have done ( via the many online calcs ) the necessary btu calc for the spaces that require AC .
Don,t forget the IN , inlets so the cabin space air can be recirculated through the air handler .Its not clear from your post how the recirculating effect is gonna work .?

The chiller marked in red cools the circulation fluid ( normally water ) then a pump , pumps that around through those short pipes blue chilled , red warmer rtn - to the air handler .

Fans with variable speed control the cabin temps ,

You need to place the chiller ( red circle ) further away with longer connecting pipes from the air handler and ideally have a seperate air handler in each space within the 24 btu vol calcs .Each air handler needs its own In and what ever out ducts .
It’s easier to route the water pipes from the central chiller to sep handlers in each space than have to route the ducting , that’s what I,am trying to point out .

Tbo - I would start again and bin that kit , it’s too inappropriate inmo.
You need to thermally insulate all the pipes - water and air too btw .

 

[vas]

Porto,

the circles and colours in your pic are correct. However, it's not a proper chiller system the way you describe it,
compressor uses some type of Freon gas that goes from the bilges to the air handler unit.
further, aircon is used 2-3 times each season for half an hour to cool the cabins before going to bed in a marina. No need to use it at anchor.
even further, I wouldn't even spend half a grand for an aircon, it's just that it was on board when I bought the boat so sorting out the installation in order to reclaim storage space.

no recirc of air either, but portlights are open so no probs there. fwiw, it draws air from the salon.

Frankly it does what I want it to do, it cools the boat, it's not too noisy (generator is much more!) and I wouldn't dare going to sleep with that thing on!

cheers

V.

 

[Portofino]

Arhh , it’s a self contained unit with one pump ( seawater ) to the cool the comp .Hence the short freon pipework .

Sorry Vas the nomenclature- “ split “ I took as seperate chiller with piped cold water to air handler(s) .
You mean the comp and air handler are not on the same chassis,presume for packaging reasons ? I would describe that as a self contained unit .
Definition turning on lack of a second cold water pump to the air handler(s) .

Aside I find it surprising and verging has on incredible that you all can sleep basically without Aircon and windows open especially where you boat

How ever us northern latitudes folks I guess are whimpy regarding temp tolerance.
Fwiw we sleep every night with the whole boat air con on in the summer , in order to get a good nights kip .
Aircon gets more hrs use than the engines :encouragement:

 

[jrudge]

Given their are two fans I would imagine it is at least possible the fans are individually controlled?

If so I would not mix them in a single plenum as if the fan were off you are going to loose air.

You may also have issues if they dont both produce the same pressure.

I would split them, with each fan cooling a similar ish sized volume of air.

The return air is important in as much as the fans must have a supply of air in order to blow.

Ideally of course it comes form the same space it has just cooled, but if not you will still need to make sure there is sufficient air "leakage" generally to the area concerned to feed the fans lots of air.

 

[superheat6k]

The unit is a reverse cycle AC system with seawater cooled condenser (round black coil) and air DX cooling evaporator coil. The reversing valve sits inside the water cooled coil.

The pipe run is quite short. I expect R407C or possibly if pre 2000 R22. I doubt it is R410A especially with flared connections on the inter-connecting pipes. Could also be R417A or R422D. If it is R134a it will be quite gutless. If it is R12 it is well past its use by date !

No reason why the two fans can't be feeding separate areas with separate controllers / stats, but a return air is essential from each zone,

If you have to dismantle the pipework I would consider getting rid of the reversing valve and make it cooling only, but this will require some brazing and then normal fridge procedures to re-charge.

 

[jfm]

Yup to all above (except portofino's). I would make a pair of Y's rather than a big "2 in, 4 out" plenum box. For reasons above -separate control of fan speeds.

Y splits are catalogue items under €20 - no need to make them. Available in all sizes. Ebay USA has lots iirc and also Coastal rides sometimes have them https://coastalrides.co.uk/air-conditioning?product_id=21663

 

[vas]

thank you all guys!

Trev. it's R22, freon pipes renewed and refilled/tested by the guys that relocated the lot in June. FWIW, works fine, produces lots (for me at least!) of cold air or hot even now that I tried it twice to heat up the boat with 0C outside (wasn't to relax and sleep in there, just get up to 16 or so so that I can work)
also there's a crappy controller that does 3 fan speeds in a toggle, 3states as in cold/off/hot in another toggle and a rotary for temp. The thing has a temp sensor wire currently lost somewhere around the stb cabin ceiling (I know not where it should be!) No mention of separate fan speeds for the two units, but sure can be done.

I could possibly setup the cabin lighting controllers which have a thermistor on them to operate the system and the fan (will be a bit of fun figuring out the 4-5cable socket that goes to each fan) but judging from the usage of the thing, I must be absolutely bored with nothing to do to spend time on that (give me a couple of years and we'll see...)
all spaces cooled/heated by the thing are adjacent to the 3mX.5mX.4m storage space under the galley/lower helm where the airhandler is fitted, so really easy to drill a couple of holes and get air from the spaces back to the airhandler. I'll do that, no problem

Regarding useage of aircon in the Med, my mate with the P45 saw me tinkering with the air con and got jealous and tried to find out if his two units work at all Apparently they do, hasn't used it in a decade that he has the boat. MapisM I think mentioned he didn't use (or didn't have?) aircon on the wooden boat of his. Mine has 50mm rockwool on all ceilings and approx 60mm polywhatever on the hull sides, so well insulated. OK, on a heatwave (42+) no wind and stuck for some reason on a port, then yes it will be hot, else it's fine for us - a Danish family that was with us for 10days this August did suffer just a bit, but was a very cool August down here and anyway spent most of their time in the water...

So, just in case, I'll do one fan two cabins, second fan galley/salon and make sure I can draw air from all these spaces. At some point later I may have a go at sorting out varying fan speed for the two sets.

cheers

V.

 

[superheat6k]

thank you all guys!

Trev. it's R22, freon pipes renewed and refilled/tested by the guys that relocated the lot in June. FWIW, works fine, produces lots (for me at least!) of cold air or hot even now that I tried it twice to heat up the boat with 0C outside (wasn't to relax and sleep in there, just get up to 16 or so so that I can work)
also there's a crappy controller that does 3 fan speeds in a toggle, 3states as in cold/off/hot in another toggle and a rotary for temp. The thing has a temp sensor wire currently lost somewhere around the stb cabin ceiling (I know not where it should be!) No mention of separate fan speeds for the two units, but sure can be done.

Outstanding ! I assume that was June 2014 that they re-gassed it (assuming you are in the EU then R22 was banned for you to for charging purposes from end of 2014).

If you need to regas again then you could use R417A or R422D although these two are now being slowly phased out due to the latest and ongoing round of gas phase outs based upon Global Warming Potential. Once these, and including R407C are gone, there won't be any replacements available with similar operating characteristics to R22.

R410A will be similarly affected. Not the time to be buying any new AC kit using any HFC based refrigerant, problem is there isn't much small kit available upon the replacement gases and R32 that is largely replacing R410A in single room equipment (splits) is very high pressure and mildly flammable. Not sure where the marine AC makers are with HFO refrigerants yet.

A simple 3 stage stat could offer a superior control of the fan, or even a simple fan speed controller and should be able to find something on Ebay for not too much cost. Let me know if you want me to look something out for you.

If your stuck with the fan wiring I might be able to help, useful to see if there is a wiring diagram anywhere, or else identify the cable marks or colours and what connects where. For four wires likely a common and three separate stage winding connections.

 

[MrB]

hello all,

trying to tidy up things and reclaim some storage space where I relocated the aircon due to the stab fitting. So this is the reverse cycle thing which features two individual fans off the same matrix (That's how I see it at least!) leading to two 125mm dia pipes:

for what it's worth it's a CLIMMA Split 24 MK3 (that's 24k btu)

and it's now under the lower helm floor with the pipework coming at a handy hatch next to the helm seat and at the moment taking most of the space for no reason.
Pump lives below next to the stbrd fin stab.

Next pic shows the preffered layout of the pipework (OK too generous in space, could well be much more compact and squashed to the right of the pic):

so top of pic is the .5m long 100mm dia hose to the stbrd cabin
mid and from the left the newish pipe is the 2.5m to the port cabin
to the bottom of the pic is the one going to the salon sofa area with a smallish tee off to a 75mm dia to the galley (combined lengths 3.5m)
just to the bottom barely visible is an oval 100mm dia outlet to the steps to the salon

Bow cabin gets a big round hatch by the anchor winch and gets free fresh air, so no air con there. Besides routing a 100mm pipe all the way there would be a bit of a nightmare tbh...

Obviously the two bigger 125mm pipes to the right are the aircon outlets.

enough with the facts, quick Q:

i'm about to fabricate two plastic or mildsteel plenums on a local fabricator.
Should I do ONE large instead with both inlets and all four outlets out of it?
Don't want the whole thing vibrating and being noisy, nor restricting flow, but sizewise and shapewise, I'm sure I can manage.

Makes sense, or crap idea?


cheers

V.

If you are trying to tidy things up in the second pic to free up some room, couldn't you use rectangular ducting to keep things flush to the side walls of the hatch? It would be a cleaner and more hygienic solution to flexi-pipes with the same throughput volume. It comes with all the bends and can terminate to round should the need for flexi-pipe situations. Here's a quick link to screwfix, it's the Manrose line I am thinking about on the web page. https://www.screwfix.com/c/heating-plumbing/ducting/cat840506?cm_sp=managedredirect-_-hvac-_-ducting