Hot Tub piping and control...

Uni R_2

Mike, it would be a purchased free standing tub. The only thing I've ever heard is that you can get some with an option to allow a boiler to do the heating rather than the built-in electric. How that all actually ties back to the boiler is what the contractor and I would like to know.

Uni R_2

Is there a standard way?

Is there a standard way of hooking up hot tubs that use the boiler instead of the built-in electric heaters? This is for down the line (I promised my SWMBO, that we'll buy one when the mortgage gets paid off in a couple of years).

Should it be done with a zone? I'm really trying to keep the house as a single zone and I can't help but think it's a low load - I have no idea what the heat loss is on those. I can't go back on the promise, but I never said how big! LOL

If it's really a low load, can it be done using the domestic, either on the boiler side or on the domestic side?

This is for future preps, but I want this planned while the contractors are doing their final piping. They don't know.

Do these hot tubs come with an HX built-in that you pipe to? I've surfed without much success.

Thanks...

Mike Thomas_2

What kind of tub?

Is this a free standing tub, or something plumbed into a pool? Is this a custom installation or something you go to your local hot tub dealer and buy?

bob young

vendors piping diagrams

ever consider following the manufacturers schematics ? or would that be too easy ?

Uni R_2

Sarcasm aside...

Yes I have, and there's nothing online that I have found in the last several days. I did go to a few local vendors but they don't have evening hours and I'm not sure if they would know given that this area is 99.5% forced air. The HX manufacturers' information is all extremely generic.

So is there a more or less standard way or not?

bob young

piping

Pick out the unit you like and contact their engineering dept. they will instruct you with their recommended piping arrangements so as you do not void their warranties.there may be several options and you can choose the one that best suits your needs. sorry if my wording offended you. i am a new yorker & you know the way we are.

Uni R_2

Bob - discouraged not offended

I actually won't be shopping for one for a couple of years. Right now I'm just having my boiler piping finalized to add in some radiant. If I need a parallel primary circuit to feed the heat exchanger and a zone controller that can give it priority those are decisions that need to be made right now. The only hot tubs I've seen have all been heated with electricity. In the meantime I have a cold kitchen floor until a plan can be finalized and this aspect is all a giant question mark.

Mike Thomas_2

no money saved

I'm not sure of your motivation for heating it with your bouler, but I suspect you think it will save you money. By the time to spend all this money to heat it with your boiler, you could have bought the electricity for the life of the tub. The next issue is service. A good voltage surge, brownout, or who knows what will cause you to call the hot tub tech out. I guarantee you he will take one look at your setup and walk away. That will leave you with a boiler guy, who will take one look and walk away. I install hydronic heating and service hot tubs, and I've never met anyone like me, they all do one or the other. Save your self a ton of money and just stick to the electric heater. Now if you are still in the mood, e-mail me direct and I can get you pointed in the right direction.

JackFre

Is it a redwood tub?

If so, I used to take the dry tub, drill two holes to allow two 1/2" brass nipples to be tightly inserted thru the openings. I'd then run two loops of 1/2 soft copper around the bottom of the tub, below the foot boards or under the seats and connect them to whatever heat source you choose. Silicone the nipples prior to pushing them thru. Once the tub fills the wood swells around the nipples and is tight. this worked very well on Redwood.

Uni R_2

Just a standard hot tub...

Thanks Jack

I was just thinking of a standard 4-5 person acrylic job. I managed to get in to the local hot tub vendor. They had never heard of heating a hot tub off the boiler - "why wouldn't you just use the built-in electric heater?" - to the tune of $500/yr I think...

Ideally I would think that the hot tub water should go through a shell and tube - major GPMs on the hot tub side.

I'm thinking that I'll leave a spot on a zone controller and just use the auxiliary 3/4" tappings that are there. I'm sort of surprised that nobody here has advice on this and that my Google efforts struck out so bad.

Happy Holidays

brucewo1b

UniR

All I can say is that I have only seen it once, I did not insatll it but had to repair a leak there once and is was done with a tube in shell heat exchanger, I know it works well and that th ho is pleased with the system.

brucewo1b

UniR

All I can say is that I have only seen it once, I did not insatll it but had to repair a leak there once and is was done with a tube in shell heat exchanger, I know it works well and that the ho is pleased with the system.

bob young

ask hot rod & brad

SOUNDS like a specialty item maybe hot rod or brad white would like to field. merry christmas from new york city

Jeff Lawrence_25

Standard way?

probably not.

Tony Connor (a long time Wallie) and I discussed this a long time and another computer ago. He may still be around and see this one day.

It's do-able and not that hard, as I remember. I never got around to it myself.

hr

Determine the load first

be sure the boiler you have can handle that tub without "borrowing" too much BTU from the heating side.

Triangle tube builds a nice small pool/spa exchanger. Also sold as a Weil McLain brand.

Youwould have to tie it into the tub's PVC piping somewhere downstream of the filter. this may be easier said than done. piping can be tight in those tubs.

Actually if it is a super insulated tub like the old Colemans, they really are affordable with the small electric heater.

With piping loss, etc, the boiler fireed could cost the same or more to moperate.

The current heater if electric multiplied by 3.41 will convert to needed BTUs.

hot rod

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Plumdog_2

Tube and shell

are what I have seen. I worked on a system recently that had two hot tubs, in different locations outside the home. The Tube and shell exchangers, the filter system, and the tub pumps were all inside the boiler room, and PVC piping ran out to the tubs; with copper loops and circs going to the boiler primary loop. See if you can get a Tub and Spa Company to divulge their methods and schematics; but the workmanship I see by those outfits is shabby; you could do better by yourself.

Uni R_2

Thanks Everyone

NG is less than 50 cents for a cubic meter here, compared to electric at just under 10 cents per kWh, so it is 2.3x cheaper per gross BTU and probably about twice as cheap given the inherent boiler inefficiencies. That's why I'd prefer to do it with gas. The Prestige is about double the size I wanted so I'm not worried about it being overloaded - and if it needs more than 30k, I don't want it. ;-)

Since there doesn't seem to be much of a standard way of doing it, I'll leave the number one priority spot open on a zone controller and assume the 3/4" tappings are fine. Just wanted to do some due diligence on this.

Happy holidays everyone...