Filling a tub with Hot Water?

[empolgation]

Any issues or concerns in filling a tub with some hot water?

I'm in the process of hooking up a hose connection directly to my solar hot water heater. I am hoping that I can use some of that water in filling my tub. I won't fill it with just the hot water as that would be too hot - in filling I would have a cold running hose in the tub and a "hot water" hose monitoring the temp along the way.

(I am planning on getting the water from the heater tested just to be sure nothing "funny" is happening to it while in the heater.)

[Spatech_tuo]

Remove the filter and fill through the filter compartment. This reduces the chance you'll have an air lock.

[Brewman]

Be sure to bypass your water softner if you have one, if you fill from an inside tap.  Switch on the bypass.
Brewman  

[Chas]

Be sure to bypass your water softner if you have one, if you fill from an inside tap.  Switch on the bypass.
Brewman  

Seems like you would have to do this in advance, or the tank would be full of nice hot soft water.

I have always discouraged people from filling with hot water. The tanks are usually full of grit and calcium just at the bottom, and some people use the clean out as a hot water tap. That basically equals cleaning your water tank out into your spa.

Assuming you use a regular hot-water tap, such as the one near your washing machine, you avoid dumping the tank into your tub, but you still have to be sure not to put in water that is hot enough to damage the surface or trip a high-limit switch somewhere.

Finally - I find that the 40 gallons or so of hot water only seems to warm the tub a tiny bit. Unless you are willing to wait for the tank to reheat over and over, you will not likely save much time in getting into hot water.

If you have a big boiler with a heat exchanger, and you can watch the water temp carefully, and if you are sure you're not getting soft water, and if you start with cold water in the bottom of the tub to keep from steaming the bottom, then go for it.

[empolgation]

Thanks so much for the input! Notes have been taken.

I have no water softener on my system so I'm good there. The water would be coming directly from the solar water heater on the roof before it goes into the hot water heater, which for the most part of the year acts as an insulated holding tank. The solar heater holds 60 gallons itself and on a sunny day it should be able to heat the water to at least 90 degrees as it flows through the panels after the inital 60 gallons is depleted.

For the future, I am considering rigging up a separate solar heater exclusively for the tub.

[Spa_Tech]

One last thing that wasnt mentioned.

Assuming you do fill your spa up with hot water and fill it through the filter compartment, there is a good chance that you will trip the spa's heater high limit on older mechanical systems- Such resets are set to pop at about 120 deg F. Running max heat water into the manifold may trip it even before you power up your system.

[Chas]

One last thing that wasnt mentioned.

Assuming you do fill your spa up with hot water and fill it through the filter compartment, there is a good chance that you will trip the spa's heater high limit on older mechanical systems- Such resets are set to pop at about 120 deg F. Running max heat water into the manifold may trip it even before you power up your system.

Yup - that's a fact. Forgot to mention it.

[empolgation]

you guys are awesome! thanks again!