I thought I would share my hot tub hookup just for into for those who may be googling this and need some info like I did.
I have an Eko 40 Boiler with 1000 gallons of storage - coupled with a Vesta System from nofossil. We acquired a free hot tub that was only a few years old and had either a broken heater or controller; according to the original owner. This summer I build a deck off our main level to support the tub. I took the side panels off the tub and insulated the best I could around the outside using 2.5" rigid foam and a few cans of spray foam.
I am running a loop off my system, in the floor joists in the basement, to the corner of the house closest to the hot tub. Here I run the loop through a 10 plate heat exchanger which exchanges heat with a glycol loop to that runs outside of the basement sill plate and alongside the deck floor joists then up through the deck into the bottom of the hot tub. From there it runs through a 55kbtu/hr titanium tube exchanger before running back into the house. This glycol loop has it's own pressure tank, air valve, and grundfos alpha pump running on the lowest power setting.
Since the tub is not right up against the house, I opted to run this glycol loop. My EKO 40 puts out a max of ~73 F (163F) water and the storage top doesn't get much hotter than this at the moment due to the limitations of the boiler controller. I thought that the heat exchangers I put in place would be plenty to get the hot tub up to temperature, however it seems this is not the case. The temperature differential isn't enough to get anywhere near my rated 55Kbtu/hr rating of my smallest exchanger; I believe this rating is at 140F differential, which I overlooked.
I am going to try modifying my boiler control to get me closer to 200F boiler output temps, for the sake of a better delta T as well as increased thermal storage in the propane tanks.
The tub will heat itself up even at 0F outdoors, but it takes a long time at my current temperature levels. I have not used the tub yet but I can only assume that the temperature loss while using the tub without a cover will be exponential during use and that the heat exchangers will not be able to keep up, causing short bathings! I am glad I added all the insulation to the tub because at this point, even without heat on all night, the temperature drop appears to be minimal.
Just some thoughts I thought I would share for the next guy. Feel free to chime in! Merry Christmas!
I have an Eko 40 Boiler with 1000 gallons of storage - coupled with a Vesta System from nofossil. We acquired a free hot tub that was only a few years old and had either a broken heater or controller; according to the original owner. This summer I build a deck off our main level to support the tub. I took the side panels off the tub and insulated the best I could around the outside using 2.5" rigid foam and a few cans of spray foam.
I am running a loop off my system, in the floor joists in the basement, to the corner of the house closest to the hot tub. Here I run the loop through a 10 plate heat exchanger which exchanges heat with a glycol loop to that runs outside of the basement sill plate and alongside the deck floor joists then up through the deck into the bottom of the hot tub. From there it runs through a 55kbtu/hr titanium tube exchanger before running back into the house. This glycol loop has it's own pressure tank, air valve, and grundfos alpha pump running on the lowest power setting.
Since the tub is not right up against the house, I opted to run this glycol loop. My EKO 40 puts out a max of ~73 F (163F) water and the storage top doesn't get much hotter than this at the moment due to the limitations of the boiler controller. I thought that the heat exchangers I put in place would be plenty to get the hot tub up to temperature, however it seems this is not the case. The temperature differential isn't enough to get anywhere near my rated 55Kbtu/hr rating of my smallest exchanger; I believe this rating is at 140F differential, which I overlooked.
I am going to try modifying my boiler control to get me closer to 200F boiler output temps, for the sake of a better delta T as well as increased thermal storage in the propane tanks.
The tub will heat itself up even at 0F outdoors, but it takes a long time at my current temperature levels. I have not used the tub yet but I can only assume that the temperature loss while using the tub without a cover will be exponential during use and that the heat exchangers will not be able to keep up, causing short bathings! I am glad I added all the insulation to the tub because at this point, even without heat on all night, the temperature drop appears to be minimal.
Just some thoughts I thought I would share for the next guy. Feel free to chime in! Merry Christmas!
