hot air or matrix ??

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ratbag

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hi folks
i have read tons of posts on this but im even more undecided
recently purchased 2 cabin beneteau 43 (2008)
brain melted trying to decide on what heating system , i had planned on using a hot air blower, eber or webaso but after being at lbs i looked at the option of water heaters with radiators and matrix outlets this one looks good value https://mvheating.co.uk/product/mv-hydro-5/ heaters

my thinking is it would be easier to install than large ducting , less heat loss
another question is, should this be installed in line with the hot water calorifier
tia
 
Hot air. Installation is relatively quick and easy. If the ducting is insulated there'll be little heat loss. Hot air requires less electrical current. Hot air is quieter than matrix heaters. The only downside versus hot water is that it won't heat your calorifier (although you'd need to change to a twin-circuit calorifier in order to hook up a hot water heater).
 
ratbag said:
thanks pvb, i will take a look at the option to fit radiators, but im now leaning towards hot air
Click to expand...

I'd go hot air. It will almost instantly blow heat through the boat, using a single fan. Matrix heating requires the water to be heated, pumped around the boat, then blown through the matrix at every outlet by a small fan.
 
I have a 41 Sweden yacht and I have the same dilemma. I had decided on matrix hydronic because of the hot water but I had a chat with the Eberspächer guys at the boat show and they were adamant that hot air was the better choice. The electrical consumption being a big factor
 
I have the matrix system on my 38' boat. I've no experience of the hot air blower system by the way.
I've one matrix in the aft cabin and one in the main cabin which has two outlets at either end of the main cabin and a 3rd outlet in the forecabin.
I find in temps below 10C it takes ages to warm up the boat and am considering having a second matrix in the main cabin to speed the heating up time. Putting the heating on when you come back from the pub doesn't get the boat warm in time for a midnight bed. Once up to heat, it's ok and great for heating the hot water and when having showers. The aft cabin with it's smaller space is fine. If I do go for a 3rd Matrix I'll take an outlet into the wet locker as well.
Mike
 
I've had both, my previous boat was a Dufour 40 with a Webasto hot air system, my current boat is a Southerly 46 with an Eberspacher Hydronic 10, hot water, with 3 matrix heaters and a second coil in the calorifier for the domestic hot water.

Before deciding to retro fit either system make sure you know how and where you're going to fit the heater and run the ducting or the water pipes, be realistic about access and how the ducts/pipes will impact on storage.

The ducting takes a lot more space for the large diameter tubes and is more difficult to bend round tight corner, you can buy hard elbows and other fitting, but these are quite expensive. To be effective the ducting needs to be well insulated and if you run the ducts through lockers, it will probably need protecting, ducts are easily crushed by the contents of the locker, when things get "stuffed into" the locker. You may also end up with quite long runs of ducting, on my Dufour the heater was mounted under the cockpit about as far aft as you could get it and there was a significant difference in the air temperature exiting the ducts between the aft cabins and the forepeak.

Hot water systems are generally easier to install and have the advantage of generating ample supplies of domestic hot water, but you need to locate the matrix heaters carefully and make sure that they are acoustically well insulated. I've mounted mine on a 10mm ply and then bonded 10mm acoustic foam to the back of the ply, the foam is then bonded to the bulkhead, forming an acoustic foam sandwich. I used normal wallboard adhesive (which has lasted 5 years to date). This significantly reduces the noise generated by the matrix heaters fans. You also needs short lengths of ducting from the matrix heater to the hot air outlets, which also need insulating, as will the hot water pipes. The Hydronic 10 has 3 matrix heaters, each with 3 outlets, which allows a good even distribution of heat around the boat.

I've looked at using radiators, but I can't find anywhere sensible to fit them, or a source of very slim radiator panels.

Having lived with both systems for about 5 years (5 years on the Dufour, 5 on the Southerly), spending over 100 days on board each year, I marginally prefer the hot water system, principally because it gives a very good supply of domestic hot water, which means I don't have to run the main engine to generate hot water (running a diesel on low load just to get hot water is not very good for the engine). However, I do miss the really hot air you get from the hot air system and the instant response, when you turn the heating system on. The Hydronic 10 takes about 10 minutes to get up to operational temperature.

I'm not to concerned about the additional power drain, the boat has a 5KVA diesel generator installed, a 100 amp mains charger, 200 watts of solar and a 150 amp alternator, but I appreciate that the additional power required for a the hot water system may be a deciding factor for some.

I'd also request that you fit a good marine silencer to the exhaust of whatever system you fit, I hear far too many diesel heaters screaming away because they aren't fitted with an effective exhaust silencer.

Hope this helps.
 
What I think would be the ideal system would be something like a Webasto Dual Top which provides BOTH hot air and hot water and is then somehow linked into the calorifier when the engine is producing hotwater. I've yet to figure how to configure it.....
 
Hot water is easier to retrofit in some boats, and provides hot showers etc too.
It can also be quieter, particularly running up the system before you wake up.
It also stores a lot of heat, so is slower to have an impact, but good for background heat which keeps the boat dry. Particularly if you let it heat the engine, which becomes a nice storage heater.
A lot of matrices are quite hungry on the DC power though. But probably better than those which were available when we fitted ours.
For a smallish boat where you're not expecting to shower aboard often, I would probably go for hot air, providing the ducting was do-able.
For a houseboat, I'd have hot water and radiators.
I know someone who has both in an off-road landy, but he did go to the arctic circle....
 
Have had both ,on a Broom 37 , hot water much more controllable and comfortable , plus hot water only in summer- eberspacher 4kw unit - relatively slow warm up
previously had webasto hot air , much quicker warm up , but little control
Ideal would be hydronic with radiators as a they even the heat out and give a more comfortable feel
 
It's worth noting that some people's experience of hot air may have been in times gone by when heaters were fairly basic. The current generation of Eberspacher/Webasto heaters are hugely sophisticated and vary their burn rate and fan speed automatically to maintain a pre-set temperature.
 
lw395 said:
I know someone who has both in an off-road landy, but he did go to the arctic circle....
Click to expand...

We have both in our motorhome :-)
The (Alde) wet system is beautifully quiet and heats every extremity of the van and if you have the time to let it heat it up then it's hard to beat.
Coming back to a cold van though after, say, a day in the hills though you need to allow 3 hours before eveything is toasty, which is when the hot air is invaluable for instant heat while the wet system is getting going.
By the way, there are no fanned/powered matrices, just lengths of convectors.

I have both an Airtronic D4 and an Hydronic D5 on the boat too, but as yet the Hydronic only heats the water but I intend to add some convectors at some point to again get the full benefit of both systems.
 
Hi , just my experiences with both systems , blown air is instant heat , but no domestic hot water, hot water matrix or rad system have one problem that most webasto units and alike only heat circulating water to circa 70 deg c , making heat out put well bellow car heater temperatures and take time to heat up , but will heat calorifier domestic water , on my last princess 30 I had both systems hot air for cabin heating , and webasto for hot water ,and worked well when no shore power and moored .
 
I'm fitting both.
I have a twin coil calorifier with an AC powered heating element. I will fit the the coolant heated fan coil to the second coil, that way when I am in the marina I can have warm air without running the webasto, also I will then have nearly 12 hours of heat from the calorifier ( I won't use the hot water at sea). Then on the anchor or mooring when I'm not moving anywhere, I will have the webasto heater.
 
Hot air will certainly heat faster and more efficiently but being able to head hot water at anchor and a towel rail for drying things is great. We have a water heat webasto which goes through the hot water tank first then to radiators and matrix blowers.

We also have a matrix heater rigged into the engine circuit which is super cheap and blows hot air better than any diesel heater could ever dream of doing.... you just have to have the engine running. It worked very well in Norway but we were often on the move.
 
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