Reverse Cycle Air Con For UK??

rich2925

rich2925

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Should I look to buy a boat for the UK which has Reverse Cycle Air con instead of Heating, my Wife would not like to be cold or to have to wait too long for it to heat up.

Alternatively could heating be retro fitted.

Obviously this is on a Med spec boat so are there any other issues with that?

Thanks
 
rich2925 said:
Should I look to buy a boat for the UK which has Reverse Cycle Air con instead of Heating, my Wife would not like to be cold or to have to wait too long for it to heat up.

Alternatively could heating be retro fitted.

Obviously this is on a Med spec boat so are there any other issues with that?

Thanks
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Med Spec is a good thing and will give you or future owners the option of where to keep here. As far as I know, reverse cycle A/C won't give the same heating efficiency as diesel heating (and will of course require 240v).

There's nothing to stop you retro fitting diesel heating (e.g. Eberspacher) to a bit with A/C (I have both on my Targa 34). On my boat the A/C is fitted under a berth and the Eberspacher unit is in the engine bay. The ducting for diesel heating is quite small so easier to thread around the boat.

To be honest, unless you're planning on anchoring a lot, a simple domestic fan heater is hard to beat.
 
petem said:
Med Spec is a good thing and will give you or future owners the option of where to keep here. As far as I know, reverse cycle A/C won't give the same heating efficiency as diesel heating (and will of course require 240v).

There's nothing to stop you retro fitting diesel heating (e.g. Eberspacher) to a bit with A/C (I have both on my Targa 34). On my boat the A/C is fitted under a berth and the Eberspacher unit is in the engine bay. The ducting for diesel heating is quite small so easier to thread around the boat.
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Agreed. I also have aircon and an eber; the hot air produced by the air con in reverse cycle mode is warm rather than hot, and in the winter months I use the eber. My installation was the other way round - I had the eber first, and added the aircon afterwards - but imho the heating installation is definitely easier than aircon.
 
jimmy_the_builder said:
Agreed. I also have aircon and an eber; the hot air produced by the air con in reverse cycle mode is warm rather than hot, and in the winter months I use the eber. My installation was the other way round - I had the eber first, and added the aircon afterwards - but imho the heating installation is definitely easier than aircon.
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Would it be possible to feed hot air from an Eberspacher to existing A/C ducting I wonder?
 
petem said:
Would it be possible to feed hot air from an Eberspacher to existing A/C ducting I wonder?
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Sounds complicated. On my boat, the eber outlets are low (= hot air rises) and the aircon outlets are high (= cold air sinks). The eber ducting is metal, I guess because of the higher temps; the aircon ducting is some sort of plastic with metal reinforcement. Finally, you'd need some sort of valve arrangement otherwise you'd end up blowing hot air into the aircon installation. So ... no!
 
When I kept my last 40- foot Sea Ray in Southampton, in February the reverse cycle heating struggled to generate much heat with the very low water temps. As the water temp rose, the heating was very good.

In the Med it was ideal, great for the air con 9 months of the year and still able to heat the boat quickly and efficiently in the winter months.

GL
 
I’ve got a water chiller reverse cycle. Works great! -2C and toasty warm.

I thought I would need to install an eber but it’s been great.

I guess it depends on the spec. Mine has 4 handlers and puts out 50c water temp no problem.
 
The issue with a water chiller reverse cycle system is that you cannot safely cool the seawater from which you are extracting heat to much below ~4oC, so as the seawater might be at ~ 6 or 7oC in Winter that means you can only cool the water 2oC, before you start having to limit the performance, and this is why heat pump water chillers do not work so well in the UK climate. In the med where I expect the seawater temp doesn't fall below 16oC you have plenty of heat available to pump.

Air cooled does fare better in this regard, with split style AC units offering effective heat pump capability down to about -5oC ambient. Below this the air rapidly runs out of usable energy, and the operaratng efficiency falls off a cliff too.

One bonus with any fridge system operating as a heat pump is the Energy Efficiency Ratio will always be ~ 1 point higher than its cooling mode operation because the heat used to drive the compressor is directly harvested as part of the heat gained. In cooling mode the driving energy of the compressor is dumped at the condenser, which is effectively what the indoor unit has become in heat pup mode.
 
A decent reverse cycle air conditioner in heating mode can output 6 or more times more heat than electric energy you put into it. I.e for 1KW of energy put in, you get out 6KW of heating.

So even if your generator, batteries and inverters are only 30% efficient in converting diesel to electricity (typical for a generator at 40-80% maximum rated load), you still get about twice the heat output per litre of diesel burnt using the generator and airconditioning system as you do by just burning the diesel for heating.
 
Thank you for all of these comments, I think I will probably see how we get on with it as it is but I have found a company who can fit Heating if we need it and the price seemed quite reasonable.

Richard
 
Had two boats with this, 1st was great at heating, we had Webasto but didn't really need it. 2nd not so good, didn't fit heating after 1st experience, did need it.:ambivalence:

We had an electric plinth heater fitted under a seat in the saloon where the main air intake for the aircon was, the aircon would suck in the warm air & pump around boat until reverse cycle eventually kicked in, problem solved.
Will see how reverse cycle is on new boat when it arrives but will fit another plinth heater if needed, was a good solution.
 
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Play d'eau has reverse cycle air con which has worked well in European waters. For heating, the fan controls are poor giving blasting warm air and dry eyes.

Hence, we fitted a Webasto water central heating. Why water? Hot air systems in boats over 45-50' often find it hard to push hot air to the ends of the ducting. And did we really want large holes drilled in the structure to take the ducts?

So now we have snug heating all through the boat when we need it. A good-looking designer radiator in the saloon, and controllable quiet fans everywhere else with demisting in the Pilot House. BTW, the two heads have electric towel rails which we run almost non-stop. Excellent clothes dryers.

So, cooling from the reverse cycle, and heating from the Webasto. Perfick.
 
westernman said:
A decent reverse cycle air conditioner in heating mode can output 6 or more times more heat than electric energy you put into it. I.e for 1KW of energy put in, you get out 6KW of heating.

So even if your generator, batteries and inverters are only 30% efficient in converting diesel to electricity (typical for a generator at 40-80% maximum rated load), you still get about twice the heat output per litre of diesel burnt using the generator and airconditioning system as you do by just burning the diesel for heating.
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I would question your efficiency argument for a diesel fired generator running a heat pump.

Indeed a heat pump 'Can' achieve an EER of 6, but at best the heat pump in the UK will give you ~ 3 or 4:1, tailing off rapidly as the ambient falls below 10oC, and the diesel will suffer tremendous transmission and stator losses, after all it is not the National grid where losses are amortised across millions of users, and at best will be working at a power factor of 0.9 or less, so I am not sure the difference will be much if anything at all, and certainly not a 2:1 net EER as muted.

When the wear and noise of the diesel is considered as well as the fuel consumption I would expect a Eberspacher will likely offer an comparable performance of likely slightly better. The pump energy for the chilled water system or fan energy of a blown system must also be included in the equation.

It would be interesting to see fuel consumption figures of an Eberspacher maintaining a cabin temperature of say 20oC v a diesel generator driving a heat pump air conditioner. I expect the Eber will win.
 
All I know is that having Eber on my V42 and now reverse cycle on my Targa 52 is awesome and keeps it perfectly hot at your desired temp, the water has to be damn cold before it doesn't function
 
Well we tried the boat on a very cold day in November and are hopefully buying, it was very warm quite quickly and we are now buying the boat so fingers crossed.

The vents on this boat were not all high level which was a point made earlier so maybe that made a difference.
 
Our F36 has reverse cycle air on, takes about 10 minutes to get warm and gets the whole boat toasty, chilly cool on last summer's hot day!
 
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