Electric boiler??

17 years ago

Hi there,

I've been building myself a new greenhouse (20' x 10') and I'm getting to the point where I need to start installing the heating. I've already established (in a very lengthy post)that I'm going to use some solar water panels with backup heat:

http://forums2.gardenweb.com/forums/load/strucs/msg0214415616399.html?41

I'm going to try a kind of underfloor heating system with a heat exchanger for the pond, so the temperature in the pipes does not have to be that high.

As the backup heat, I'm thinking of using one of these electric boilers made for small rooms and conservatories (something similar to this: http://forums2.gardenweb.com/forums/load/strucs/msg0214415616399.html?41) I'm just wondering if anyone has any views on this type of heater? Do you think 2kw be sufficient (to keep the greenhouse above 15C)? I'm thinking of building a couple of solar air collectors, along with the solar water panel so around 2kw I think might just about be enough. I'll keep a fan heater nearby incase a very cold night comes along but these boilers might just be the extent of my budget (along with those bloody expensive solar panels) so I don't think it would be worth spending more on a higher powered heater.

Has anyone ever used one of these in their house/greenhouse? I'd love to hear how well they work.

Thanks,

Hen

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Comments (3)

mokevinb
17 years ago
Hen, Here in the U.S. the use of hot water radiant heat is again becoming popular, but is still limited in the total number of applications. What you are describing is sort of a hybrid between a heat pump and a boiler/solar collector. There are some companies over here that are offering a solar collector system along with a ground loop geothermal heat pump, but they are not very well known. I was wondering why you are chosing to go with an electric boiler. Over here a gas fired one would be more popular and common. The price between electric and gas boilers here are very close to the same, so the only difference is available fuel sources and owner preference (in some areas gas is much cheaper than electric for the amount of btu's you will derive from it.) Another reason gas is more popular is that the burner only kicks on when there is a demand to raise the temperature of the water in the loop. Overall, I think your idea is great. Use both the ambient temps of your pond, and then use solar heat to raise the temp the rest of the way, with the boiler only for below optimum temps. Great thinking!
hen11
Original Author
17 years ago
Hi there,

Thanks for the compliments! from what i've seen, the small one-room electric boilers on ebay are around Â£100 which is far cheaper than a full gas boiler system set up in the greenhouse.

I'm choosing to go electric because to rig a gas line right to the end of my garden would be pretty difficult/expensive. I've already got a mains electric socket in the greenhouse so it would be far easier to just plug in and use.

I'm hoping to raise the room temp along with the pond temp so the evaporative cooling in the greenhouse is less but there is still a fair amount of humidity from the pond. I think I'm just going to run some copper piping under the path and around the walls.

thanks,

Hen
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mokevinb
17 years ago
Hen, rather than using copper for your conductive piping I would like to recommend that you look into a product called PEX. It is a reinforced plastic material and is in greater use in Europe and the UK than it is here. PEX is sold by the roll and you use compression type fittings to put it together or make connections to your appliances. The reason why I am recommending PEX over copper is the ease of installation, and durability. Copper requires you to solder your fittings together and is more prone to leakage due to acid breakdown. Here in the U.S. we tried using copper for radiant heating under/in concrete during the 1950's 60's. We found that the acid within the concrete eats at the copper and will cause leaks. Pipes buried within concrete are thus at a much greater risk of failure. With PEX, if a leak develops it can easily be repaired with simple tools and compression fittings, provided it can be accessed.
Here in the U.S. a 50 gallon electric or gas hot water heater/boiler can be bought new for about $225.00. I fully understand the issue of availability of a fuel source. If a gas line is not near your greenhouse, then the cost of installation might be a factor in not going with gas. Of course there is also the issue of venting. My one recommendation is to make sure that you either buy a very well insulated boiler, or you put on an insulation blanket. We can get these at any home center and most hardware stores.

Electric boiler??

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mokevinb

hen11
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Electric boiler??

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hen11Original Author

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hen11
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