Reverse cycle Air conditioning anyone?

[Trawler]

Given our increasing days of very hot weather, has anyone put air conditioning in a narrowboat?  I don’t mean a RV unit purchased on the roof, but something like a reverse cycle unit (heat pump)  (which is common in larger boats and hidden from view and outputted through heating ducts which are also non existent on narrowboats as all I’ve seen have radiators).  It does require the use of the genset running though.  I’d like to commission a new narrowboat and was thinking of the practicality of this. My guess is it isn’t practical but would sure be nice some days. 

[Guest]

5 hours ago, Trawler said:

Given our increasing days of very hot weather, has anyone put air conditioning in a narrowboat?  I don’t mean a RV unit purchased on the roof, but something like a reverse cycle unit (heat pump)  (which is common in larger boats and hidden from view and outputted through heating ducts which are also non existent on narrowboats as all I’ve seen have radiators).  It does require the use of the genset running though.  I’d like to commission a new narrowboat and was thinking of the practicality of this. My guess is it isn’t practical but would sure be nice some days. 

 

Ducted leisure vehicle units that dont sit on the roof are available.

 

Truma do a couple depending on output and features  required.

 

https://www.truma.com/int/en/products/truma-air-conditioning/truma-saphir-compact

 

https://www.truma.com/int/en/products/truma-air-conditioning/truma-saphir-comfort-rc

 

 

Edited July 1, 2022 by The Happy Nomad

[magnetman]

Interesting items. They seem to require some sort of vent or exhaust below the unit. I suppose if it were mounted high up somewhere it would work maybe routed out the side of the boat ? 

 

Those and the Dometic Freshwell (same thing?) do look quite nice. 

 

Prices not too shocking 

 

https://www.ebay.co.uk/itm/394123868209

 

Nice luxury to have. 

[Tony1]

 

I've thought about something like this, but not taken the plunge.

The smaller of those units is almost feasible. On the hot and sunny days when you need it, I usually get 50-80 amps of solar charge for most of the afternoon, so it can effectively be run on solar power for several hours in my case, with minimal running down of the batteries.

 

The thing I'm not sure about is whether my inverter could handle the start up current of 15 amps at 240v, which if I'm right means it will try to pull around 300 amps from a 12v battery bank and through the inverter (my 1000 watt immersion heater pulls about 80-85 amps from the batteries). 

 

But if you are building from scratch you could of course spec the inverter and batteries and solar to cope with one of these. I would rather have at least 600Ah of lithium batteries rather than my current 400Ah, if I was planning for one of these pulling 60 amps for hours on end. But the experts here will hopefully add a sensible view on that.

 

Its not been on my mind a great deal as we've had very few heatwave type days so far this year, and none as bad as the ones we had last summer. 

I may think differently about this after we've had a half a dozen of those awful sweltering days, but the problem I keep coming back to is that even the compact one is a fair size, and for most of the year it would be sitting unused and taking up storage space that is already not nearly sufficient, on my 50ft boat.

 

Perhaps with a bigger boat or better organised storage you could find a home for it somewhere. I'd love one tbh.  

 

 

[magnetman]

I'm quite tempted by one of these for my residential mooring boat. It's only a little boat but being a deep sea boat it has a lot of spare volume inside. More difficult on the off grid boat but doable with the right hardware. 

 

Startup current is definitely an interesting question. 

 

It does heating as well which would be quite nice on a boat with mains connection. 

 

It says down to +2 Celsius outdoor temp for the heating so below that one would have to get the fire going and make smoke. 

 

 

Edited July 1, 2022 by magnetman

[Thames Bhaji]

I’ve been tempted too, but I’ve been looking at water-source rather than air-source. The units above would be trying to exchange heat with warm air in Summer and cold air in Winter, while the river / canal would mostly be at a more useful temperature, and easier to exchange heat with. The ones I’ve looked at are also more expensive and require more plumbing & through-hulls however… hence I haven’t been tempted enough yet. 

[Guest]

Our roof mounted version which is similar in spec. will start up and run on a 6 amp site supply without tripping it.

[Alan de Enfield]

1 hour ago, Thames Bhaji said:

I’ve been tempted too, but I’ve been looking at water-source rather than air-source. The units above would be trying to exchange heat with warm air in Summer and cold air in Winter, while the river / canal would mostly be at a more useful temperature, and easier to exchange heat with. The ones I’ve looked at are also more expensive and require more plumbing & through-hulls however… hence I haven’t been tempted enough yet. 

 

We planned to put one of those water source ones in our boat, nearly signed the order when the guy said "where will you be using it ?" it turns out that above an imaginary line extended East & West (Wrexham, Birmingham, Leicester, the Wash), the sea is too cold and when you need heating the most you won't get any. Inland waters will no doubt be warmer than the sea but it is not a reliable source of heating so you would still need you SF stove or Eberspacher.

For cooling it would work well, but for the odd few days a year is it really a viable option ?

[IanD]

6 minutes ago, Alan de Enfield said:

 

We planned to put one of those water source ones in our boat, nearly signed the order when the guy said "where will you be using it ?" it turns out that above an imaginary line extended East & West (Wrexham, Birmingham, Leicester, the Wash), the sea is too cold and when you need heating the most you won't get any. Inland waters will no doubt be warmer than the sea but it is not a reliable source of heating so you would still need you SF stove or Eberspacher.

For cooling it would work well, but for the odd few days a year is it really a viable option ?

 

I looked into this extensively when designing my boat (no power problem since it's a hybrid with a massive 48V LFP battery bank) -- specifically, this (water-source) one...

 

https://www.advanceyacht.co.uk/marine-air-conditioning-units-all/p/frigomar-scu16vfd

 

Efficient as both a heater and aircon (~1kW maximum input power for ~5kW heating/cooling -- this is the biggest one, there are smaller cheaper ones too) and no inrush current, but not cheap.

 

What stopped me was that as Alan says it needs a minimum input water temperature of 5C so won't work all year round for heating on the canals, and also uses fresh water from the canal so you need an intake, mud box, worry about clogging up etc. -- also awkward to fit in the required air ducting in a narrowboat. So I'd also have needed a second heating system as well.

[Thames Bhaji]

3 hours ago, Alan de Enfield said:

For cooling it would work well, but for the odd few days a year is it really a viable option ?

I decided it wasn’t worth it, and instead went for increasing air flow through the boat which uses far less power. Last year I cut a 12” hole in the cabin top below one of my PV panels, cut the middle out of a stainless dish and used it as an upstand, and mounted a 9” radiator fan into the ceiling cavity. Basically a giant mushroom vent. At full power it’s like a gale blowing through!