Outdoor Wood Furnace Info
All-Purpose OWF Discussions => Pools & Hot Tubs => Topic started by: kybaseball on January 29, 2012, 03:12:40 PM
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Ok I have to ask. If I get a hot tube that would seat outside on my deck and use my OWB to heat it how would you control the temp. in the hot tube? If anybody is doing this I really would to know how it works. I don't want to hook it up to electric at all.
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You would have a water to water heat exchanger designed for pools and hot tubs mounted on it. It would be a stainless shell heat exchanger. Temp could be controlled by a zone valve or somethingof that nature depending on your design. It will work and work well :)
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This is a subject that interests me. I would like to know about how much more fuel consumption would result. What do you keep your temps at? If you lower them when not in use, how long does it take to recover?
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I've had folks say they keep them on 102 and never see much difference in wood use as long as the insulated cover was on.
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I keep mine at 102 to 104 at all times 24/7 12 months a year. I installed the tub in 2008 and have been heating it with my boiler since 09. Now, my tub has a small cirulator pump that runs 24/7. I think that if my tub did not have this, it would be more difficult to hook up. I control my temp with the tub controls just like normal. You can't tell the difference between wood or electric heat for setting temp.
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Dirtryder, Do you fire your boiler year round?
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Dirtryder, Do you fire your boiler year round?
I did all last summer. I installed my 6048 last Feb and it has been burning ever since. I was curious to see how much wood I would use to keep the tub and DHW going during the summer. We also just had a pool put in and filled on Labor day last year. Was heating that also till I winterized it. In the summer i put about one wheel barrel full of wood every 36 to 48 hours. I was suprised that the boiler never went "out" due to the light load. Now, when I finally hooked the pool up.......well THAT takes some wood!
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you can figure on spending around $1000 in hooking up to your hot tub. it works very well an i can't see much in the way of wood use ,might be a cord a season or less. we keep the temp at 103-104. i figure we have been saving just on the hot tub $35 a month. it will take awhile to recover the initial cost. it sure feels good in there when it's 10deg outside ;)
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The place I moved into has a hot tub that is very dilapidated. I will be ripping it out and getting a new one. Well, new to me anyway. I just went outside to see what size heat exchanger it had, and there are just two hoses (maybe 3/4") that come from the copper supply and return on the side of the house. Someone decided to take the exchanger with them. So now I am faced with a dilemma. I am renting this house, so I want to be as cheap as possible. I am willing to buy a used hot tub, knowing I will leave it here. But the price I am seeing for tube and shell exchangers is ridiculous. How would the plate exchangers do? I am willing to use electricity to heat the tub when we have the cover off.
Also, I saw that I can use a zone controller for temperature regulation. Is that just a valve that bypasses the exchanger? So I could adjust the valve to divert say, 40% in a loop back to the OWB instead of the exchanger?
I don't know if they plumbed this system the best possible way.
Mine goes OWB-> Hot Water Heater -> Furnace (Water to air) -> Hot Tub, than starts its return to the OWB to be heated and start the cycle again. There are shutoffs for the hot tub,(at the wall the pipes go through in the basement) so I could in theory control the flow of supply or return to the hot tub, but that would effect the flow on my entire system.
I see jimr said I could expect 1000 to hook up the tub, I hope to come in at the 200 or less mark, since the 1" (Maybe bigger) copper lines are already in place and snaked through the basement.
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You could use a plate heat exchanger but it won't last very long compares to the proper heat exchanger. It would be worth spending the extra $40 or $50 on the pool heater and then taking it with you if you leave just like the last people did. You could resell it at that time and it would have some value but the plate would be junk.
To control it you need to use a zone valve or pump unless you want to manually control the temperature.
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That would be a possibility. The price difference I have seen between plate and tube is quite large. Does anyone know of good sites to get exchangers from?
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What kind of prices have you seen? A 20 plate is usually around $190 and a smaller pool heater is about $240.
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Another option you might want to consider if you go cheap,I have a used 10 plate.
I would setup a secondary loop for it though if you use a 10 plate so it doesn't restrict your boiler flow. (both tees in the same pipe, not one in supply and one in return)
It would be about $150 with a used pump. I would think you would get a few years out of it but depends on how fast the chemicals eat the brazing.
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Thanks RSI! If I was going to go with the 20 plate, I probably would just go with the tube exchanger, but from the BTU ratings I have read, a 10 plate would work. I will admit first off, I know nothing about heat exchangers other than the basic fact that they transfer heat. Would the plate exchanger last longer if it were inside? Or is it the hot tub chemicals that destroy it, or just how/what they are made of never stand the test of time?
I have also thought about using a sidearm exchanger, though I am unsure how well it would perform. I have found them right around 120 in many places.
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check out freeheat4u.com and check out the shopping cart. Thats where i got mine. They have the best prices ive seen so far
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Thanks RSI! If I was going to go with the 20 plate, I probably would just go with the tube exchanger, but from the BTU ratings I have read, a 10 plate would work. I will admit first off, I know nothing about heat exchangers other than the basic fact that they transfer heat. Would the plate exchanger last longer if it were inside? Or is it the hot tub chemicals that destroy it, or just how/what they are made of never stand the test of time?
I have also thought about using a sidearm exchanger, though I am unsure how well it would perform. I have found them right around 120 in many places.
A 10 plate will give you plenty of BTUs. Most people go up to a 20 plate just because of less restriction.
It is the chemicals in the hot tub water that will destroy the heat exchanger. Going with a side arm wouldn't have the flow restriction of a 10 plate but being plain copper will be even worse than the brass brazing on a plate heat exchanger.
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I have a OWB and am getting a hot-tub. I want to heat the hot-tub in the winter with the water from my boiler. I have viewed one persons setup like this, however they did not have an electric heater in their hot-tub, they had removed it and simply went entirely with the heat from the water-to-water exchanger. I would like to see another configuration where folks have not removed the electric heater from the hot-tub, so I can get an idea how and where penetrations were made into the lines of the hot-tub. Also, I would like to see the other components, other the the exchanger and how they have been connected. If someone out there has information on their own installation of a water-to-water exchanger and a simple yet effective way for me to do the same, I would appreciate the help. My OWF handle is gsilus, so perhaps that would be a good way to contact me at first. Also, if someone reading this is in the Minneapolis/St. Paul metro area and they have such a setup, I would like to visit and see how you connected your system up. Thx!
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I have never personally hooked up a hot tub myself but it I was doing it I would take a line on the hot tube after the pump and run it to the heat exchanger and then back to where it was going. Then I would cut the boiler line in the most convenient place and put 2 tees right next to each other in the line and a pump to pull water in the first tee then to the heat exchanger then back to the second tee.
Then all you need to do is hook the pump's power up to a thermostat to control the hot tub temperature.
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in my hot tub there is one jet that is on all the time . i cut that line and in and out of the tube heat ex. for best results your pump should run 24/7. i have a ranco t-stat probe attached to the line i spliced into to work a zone valve. i just backed down the electric heater t-stat to 70deg. so it does not come on at all. my hot tub goes through several cycles a day and stays withen about 3deg.for what it is set at. everything is mounted inside the tub cabinet.
as for wood use ,it's not much.