Hot tub hookup DIY

[jfriesner]

My first post on here but definitely not my first time o the site. I have been gleaming lots of useful information off this and other sites.

I just wanted to share my OWB hookup and how i'm heating my hot tub. My boiler I got is a 90's Heatmor 200css model I traded labor from a friend for. I refurbished and cleaned it, it had sat in the woods for several years unused. I also got some brand of Thermopex from him that was also used. My system is run off one Taco 007 pump that is on the low end supply side of the boiler. It runs 65' to my house about 30" down but surfaces and goes through the back wall of my house into the furnace room. It then feeds a 24" sidearm, 40 plate ex for on demand hot water, it then goes to the hot tub ex, which is the exact same tube style as my sidearm, and then to my forced air furnace heat ex and back to the boiler.

Total loop length is roughly 300' round trip of 1" pex. With nothing calling for heat I have a Delta T of 4degrees. That is with roughly 15' of completely exposed thermopex sitting on top the ground and an outside temperature of -1F.

The hot tub I got for free and was a huge PITA to clean but has been awesome to have, kids love it! Its a 1991 Calspa and holds 1200gal of water. We keep it at 104F 24/7 and as you can see not the best cover on it. I T'd into the 2" supply line and reduced it to 1" pex that goes to the Taco 007 pump and then its reduced to 3/4" pex to the heat ex and then dumps into the 2" return line back to the tub. I completely bypassed everything to heat the tub. The only thing I use that the tub came with is the pump to run jets and clean the spa on a timer. The heat kicks on and off with a high limit aquastat T'd into the 1" pex supply just before the pump. It is a very simple system that didn't take much to get operational. It has been up and running for 2 weeks now with zero issues. The tub is always 104F and we use it quite often.

I live in central MN so we have been seeing mostly teens and even single to below zero weather. I have seen very little difference in wood consumption with hot tub added on. I have an exactly 1/2 cord rack right next to my boiler so i can keep very good track of consumption. This is my first year with the boiler so unfortunately burning green wood mostly and i'm sitting at 1/2 cord every 12 days with the temps as stated above.

If anyone has questions on how I did the hot tub I would love to help out. This site has been so helpful to me!

Thanks

 

[stee6043]

Nice photos. That's a massive tub!

Around these parts you'd likely be on-track to have a 13 +/- cord winter. That's a whole lotta wood. My back hurts just thinking about it.

Thanks for sharing. I think there are quite a few around here with spas....

 

[jfriesner]

Ya the tub was much larger then I was looking for, cabinet measures 8'x12', but free is free. I ripped the skirting off and re insulated the cavity and then put 1.5" foam on the outside. It seems to make it very well insulated. The cabinet where all the mechs are stays at around 95F, I have a wireless thermometer in there to keep track of it incase of a malfunction.

As far as wood goes we have 40acres of timber and I have a 16' dump trailer, wood wagon, ATV, Ford 3000 tractor, and a splitter. What i did was paid $281 for a 24hr mini excavator rental and collected dead and downed trees on my property. I got 12cord in one day and I even spent a good chunk of that digging stumps and blazing some new trails. It was easy work and now I have at least one year of wood within feet of my boiler. I'm just gonna plan on renting that machine once every year and get all my wood in a day for a reasonable price and my land improves every year too.

 

[jfriesner]

Quick update. The tub has been operational since end of november without issue. We recently went into the deep freeze for about the last 10 days and looks like we have a few more days to go of this. We've mainly been in the single digit daytime highs with nights dipping well below 0, -20 to -30 frequently. The hot tub is always at 106F and I am still easily getting 12-18hr burns out of my heatmor. I frequently load it at 5-6 in the evening and don't add more until 9-10 the next morning with plenty of fire to get the next load going. We use the tub pretty much daily and the kids love watching the giant column of steam rising when its -20 or so.

The only minor issue is my kids left the jets on one day for about 6hrs before I caught it and with the jets going it was able to create a thermal siphon and it over heated the tub to 128F. Glad I caught it. It didn't damage anything luckily but I will probably add zone valve this summer to completely close off the heating plumbing that i added so that can't happen.

 

[maple1]

Can you put a timer on the jets?

 

[jfriesner]

That would be another solution and perhaps a better one. Good thought!

 

[Highbeam]

Modern tubs, well mine anyway, shut off jets after 15 minutes.

 

[jfriesner]

Modern tubs, well mine anyway, shut off jets after 15 minutes.

Ya mines a 1991 Calspa and has very few options compared to modern tubs. What it does have going for it is size. 1200gal tubs are hard to come by.