Heaters and Dehumidifiers

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derekbland

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Advice please. I know I have seen a thread on this but can't find it.

I have a motor cruiser with a total of 4 cabins including the crew cabin. I already have.

* One medium size oil filled rad and 2 smaller ones left with the boat
* There are 3 or 4 cobbled together heaters with what look like a kettle heating element with a cage on top. Look a bit iffy to me and so likely to throw them

Questions;

What additional small bar heaters do you recommend?
Where would you place them?
What dehumidifier would you reccomend?
What about this one? https://cpc.farnell.com/hylite-ecoh...OSri96YbjHqVpIfFrY19dIi-U5Pea1YxoCeLIQAvD_BwE

Happy with where I place the dehumidifier as it will be in the galley with the drainage pipe in the sink.
 
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Purely for keeping the boat unfrozen I would have 2-3 tube heaters in the engine room. For a dehumidifier make sure it's a dessicant dehumidifier so it won't be affected by the cold - sited in the galley keeping internal doors open will be fine. I find the dehumidifier does pump out quite a bit of heat too, so that can be useful.
 
It depends where the boat is based over winter and what sort of winter we get, ie how long is a piece of string! The tube heater you linked to is only 55W and will struggle to keep the engine room above zero over winter if you are based on the S Coast. Bear in mind the sea froze over at Bembridge in January this year.

I had 3x 120w tube heaters, 1 under each engine and 1 in the lazarette with all the thermostats set to max during Dec, Jan and Feb. Boat in the water (Solent) over winter and min temp in ER was recorded at 4 degrees. If the boat had been laid up ashore the ER would have been dangerously close to freezing. Get some min/max themometers so you can monitor what happenes between your visits to the boat or better still get a couple of thermotex sockets so you can remotely monitor ER temp in real time. Far less to worry about above deck, +1 for a Meaco dessicant type dehumidifier draining into the galley sink and wedge all the doors open with towels to allow air to circulate. I also take the curtains home over winter to ensure no chance of mildew.
 
If you are not planning to use the boat over the worst of the winter I would winterise the engines and gennie (and aircon) - run an antifreeze mixture through the sea water system. No worries about electricity supply etc.
Drain all the drinking water from the tank and open all the taps and shower valves - don't forget the shower on the bathing platform if you have one.
Then just have a de-humidifier in the galley on a timer so it runs for a few hours a day only.
 
kashurst said:
If you are not planning to use the boat over the worst of the winter I would winterise the engines and gennie (and aircon) - run an antifreeze mixture through the sea water system. No worries about electricity supply etc.
Drain all the drinking water from the tank and open all the taps and shower valves - don't forget the shower on the bathing platform if you have one.
Then just have a de-humidifier in the galley on a timer so it runs for a few hours a day only.
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Thanks Mark. Regards the transom shower it runs up from the back of the crew cabin. The pipework is behind a cover at the rear of the cabin. I guess best solution would be to remove the cover and have one of the small oil filled ones in there. Also, do I need a heater in the saloon with the dehumidifier going?
 
+1 for the Meaco link. The dessicant type still function at low temp, unlike refrigeration ones. When you switch it off , it has a powerdown cycle to ensure long life of the rotating dessicant wheel, so it's recommended not to use it with a timer. Its internal timer samples the humidity every few minutes and decides whether to start up not. MIne has been through a few Marina power outages but still functions well 5 years on. The design is a bit top heavy imho so I lash it in place when the boat is afloat to prevent it toppling over.
 
Thanks guys looks good and so will be ordering one.

One more question, when would you set up your heating etc. October, November?
 
derekbland said:
One more question, when would you set up your heating etc. October, November?
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Depends if you are on metered electricity and how far you are from the boat. When I had the boat in the UK the dehumidifier was left on all year and I put the heaters in place in November with frost stats on them all. We did use the boat most of the year but if very bad weather forecast I would pop to the boat and put a cabin heater on and turn the tubes on full time. If the boat is ashore I would leave them all on from Nov
 
markc said:
Depends if you are on metered electricity and how far you are from the boat. When I had the boat in the UK the dehumidifier was left on all year and I put the heaters in place in November with frost stats on them all. We did use the boat most of the year but if very bad weather forecast I would pop to the boat and put a cabin heater on and turn the tubes on full time. If the boat is ashore I would leave them all on from Nov
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I'm on a meter but my view is that a little extra on electricity is better than the cost to repair burst pipes. We are quite a way away and so can't just pop down to the boat and so will leave on thermostats.

Thanks again for the advice. I am back down there early October and so will set it all up then.
 
I live less than a mile from the boat so can respond promptly if frost is forecast.

However I will probably take the dehumidifier and frost protection heaters to the boat in late October with a view to starting to use them in November. I have a plug in temperature controller for one of the heaters which doesn't have its own thermostat.

I will also drain the domestic water off some time in in November . A couple of degrees of frost is no threat with the boat in the water.
 
markc said:
Depends if you are on metered electricity and how far you are from the boat. When I had the boat in the UK the dehumidifier was left on all year and I put the heaters in place in November with frost stats on them all. We did use the boat most of the year but if very bad weather forecast I would pop to the boat and put a cabin heater on and turn the tubes on full time. If the boat is ashore I would leave them all on from Nov
Click to expand...

If I have the dehumidifier in the saloon, do I need a separate heater in the saloon? I will have an oil filled further down by the cabins plus the suggested engine ones and near the genny. Also one in the crew cabin placed near to the pipework for the transom shower.
 
Derek

I assume your objectives are 3-fold:

1. Ensure the fresh waster system doesn't freeze.
2. Ensure the engine(s)/gennie don't freeze.
3. Stop the accommodation from becoming/smelling damp or moldy.

1 and 2 are primarily about what you do to winterise the boat, rather than the number or positioning of heaters. On my boat I cannot guarantee to eliminate all water in the fresh water system without dismantling every join. Even then, I couldn't be sure. So, I deliberately leave in a small quantity of non-toxic antifreeze solution (Freezeban or Starbrite) which can protect down to -15C if used in concentrated form, and make sure that is properly distributed around the system. After a couple of cracked transom shower heads (before using antifreeze), I now make sure to remove it entirely, just to be safe. If you have done this, you shouldn't need to worry about heating the transom shower pipework specifically, as we are unlikely in the UK to experience temperatures that would bring the internal temperature down as low as -15C.

Similarly, proper winterisation of the engine ought to ensure you don't have any problems caused by freezing. Same with a gennie.

So, if both 1 and 2 are sorted, all you need is enough heat in the boat to ensure that your dehumidifier (whichever model you choose) can work enough of the time to keep the air free of damp. And that should be possible with a heat source close to the dehumidifier. (Note that a dehumidifier does not need to be able to work efficiently all the time if the boat is already dry inside, since the amount of moisture that will be brought into the boat when the temperature outside of the boat is hovering around the zero mark will be relatively low - damp air that is cold doesn't actually contain much moisture).

Now, admittedly my boat is small compared to yours - just 2 cabins in 40 ft - and, being a raggie, all the accommodation is on one level. But I find that putting my SINGLE heat source, in the saloon, next to the dehumidifier is sufficient. I simply ensure that all cabin/heads doors are wedged fully open and the cover to the engine compartment too. I use a greenhouse fan heater on its lowest temperature setting, rather than oil filled rads.

Now, I don't know how this all translates to a big mobo. Maybe air circulation isn't as easy when you have 2 storey accommodation. But your solution sounds a bit overkill compared to what I "get away with".

Remember to flush out the antifreeze from the freshwater system in the spring before making a cuppa. :)
 
Angele said:
Derek

I assume your objectives are 3-fold:

1. Ensure the fresh waster system doesn't freeze.
2. Ensure the engine(s)/gennie don't freeze.
3. Stop the accommodation from becoming/smelling damp or moldy.

1 and 2 are primarily about what you do to winterise the boat, rather than the number or positioning of heaters. On my boat I cannot guarantee to eliminate all water in the fresh water system without dismantling every join. Even then, I couldn't be sure. So, I deliberately leave in a small quantity of non-toxic antifreeze solution (Freezeban or Starbrite) which can protect down to -15C if used in concentrated form, and make sure that is properly distributed around the system. After a couple of cracked transom shower heads (before using antifreeze), I now make sure to remove it entirely, just to be safe. If you have done this, you shouldn't need to worry about heating the transom shower pipework specifically, as we are unlikely in the UK to experience temperatures that would bring the internal temperature down as low as -15C.

Similarly, proper winterisation of the engine ought to ensure you don't have any problems caused by freezing. Same with a gennie.

So, if both 1 and 2 are sorted, all you need is enough heat in the boat to ensure that your dehumidifier (whichever model you choose) can work enough of the time to keep the air free of damp. And that should be possible with a heat source close to the dehumidifier. (Note that a dehumidifier does not need to be able to work efficiently all the time if the boat is already dry inside, since the amount of moisture that will be brought into the boat when the temperature outside of the boat is hovering around the zero mark will be relatively low - damp air that is cold doesn't actually contain much moisture).

Now, admittedly my boat is small compared to yours - just 2 cabins in 40 ft - and, being a raggie, all the accommodation is on one level. But I find that putting my SINGLE heat source, in the saloon, next to the dehumidifier is sufficient. I simply ensure that all cabin/heads doors are wedged fully open and the cover to the engine compartment too. I use a greenhouse fan heater on its lowest temperature setting, rather than oil filled rads.

Now, I don't know how this all translates to a big mobo. Maybe air circulation isn't as easy when you have 2 storey accommodation. But your solution sounds a bit overkill compared to what I "get away with".

Remember to flush out the antifreeze from the freshwater system in the spring before making a cuppa. :)
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Brilliant. Thank you
 
+1 for Meaco. I do use mine with a timer and never had any problems. The guy that sells them for Meaco said his dad has a boat and uses one on a timer without any problems. I am on my second Meaco with the first lasting a very well used 9 years.

In Scotland we can have regular -0c in the winter and whilst the boat is in the water, we have all the domestic water etc.... as normal. I put a bar heater under the engines, one on top of the water tank, one beside the fresh water pump and one beside the calorifier. The Meaco runs for about 6 hours a day on a timer.

Never had a problem with damp or worse. Out of the water the precautions are bit different and are increased quite a bit.

We use the boat in the winter, as a caravan or out in the water as sometimes the cold snowy days can be flat calm and stunning.
 
Now the proud owner of a Meaco as suggested above. Having a play with it in the lounge. Will take it down to the boat early Oct when she is also due for a service.
 
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