Hydronic bathtub

hot_rod

or flush it daily. It's too much of a legionella risk the way you have it.

A small 2-1/2 gallon or 6 gallon electric HW tank would be an excellent heat source. Or the small Laing combo, although a bit oversized in wattage.

hr

Mike Dunn

Ok so call me crazy

but I think this is going to work.

I wrapped 70 ' of 1/2" aquapex around a Maax 32" x 60" air tub from the bottom of the tub to right below the overflow line. The tubing is fairly tight to the tub and will be surrounded by fiberglass installation before permantly mounting it.

Once the owner starts drawing water to fill the tub, a bronze circulator will come on and pump domestic hot water(120 degrees max) around the tub in an attempt to keep the water in the tub hotter, longer.

My concern is stagnation in this loop. My thought is to put a timer on the loop and purge it once a day or something. But I also need to turn on the pump at random when the owner wants to take a bath.

Any thoughts?

Mike

Derheatmeister

Block Heater?

If you got a Boiler you can interface it with that

If you have a Furnace and have no other Hydro heat then i would interface it with and small Electric water heater/Circulating Pump which is not interfaced with your Domestic water.!

You can also use a heat exchanger off of the water heater.

If you like to experiment check at "Napa" for the inline 110V/1200W;1500W Engine Block heater maybe you can use this with a small circ?

You can also interface a "Towel Rack" on the same system.

As Hot Rod said keep you Domestic water separate!

Rudnae

why not...

Why not just have the pex tied into the line feeding the valve? That way it is the same as the supply line and there should be no additional worries about legionaires, etc. I use something similar to prevent the mirror from fogging up, with a pressure ballanced loop (figure 8) behind the mirror, it works great!

George_40

airjet tub

I know this is probably a little too late, but in case you didn't know they do sell airjet tubs with built-in heaters already.

MERRY CHRISTMAS!
G

Mike Dunn

They sure do

but I still get complaints of the water cooling quicker than the customer would like.

Mike Dunn

I thought

of this, but once the tub is filled the flow around the tub stops. I'm not sure this will contribute much to the continued warming of the bath water.

I do like the idea of a separately heated closed loop system around the tub. I'm going to give this idea some more thought.

Haven't installed yet. Scheduled for 12/29

EJW_3

Radiant tub

Maybe I am missing something, but if you have a boiler why not just pipe it up with a thermostatic mixer and put the circ on a light switch in the bathroom? Not next to the tub of course. Walk into bathroom and flip on switch, fill tub, take bath, empty tub, flip off switch.

EJW

Mike Dunn

No boiler

Just a domestic water heater and a forced air furnace.

Tombig_4

I have a carefully adjusted microswitch to detect joist deflection when there is a load in my tub but I use that to run a dedicated zone from my boiler.

With DHW as the heat source, I guess you could put the tub in the return of a Hot water recirculating loop and bypass the temperature sensor with the microswitch for continuous circulation when the tub is in use.

Ron