More hot water for whirlpool tub

[bikeboy]

I've posted here before about filling a 84 gallon whirlpool tub. I have 2 - 50 gall. electric WH's opposite ends of house. 1- 50 gallon wont cut it for tub fill. I'd rather not move WH's together, or tankless, and use circulator; only 2 of us living in house. Is it possible to just bring a 1/2" line from WH circuit#2 hot side , and T it into whirlpool tub spiket branch to add hot water to feed tub with WH#1 ? could I just T the two circuits, install a mini tank, or mixer to combine them @ tub's@hot side ? If so, please describe how. I've also considered a small point of use WH near tub as an addition to existing unit, but only puts out .5 gpm.

HR...

 

[Jadnashua]

If the two hot lines are not now connected together, because of the significantly different run lengths, balancing them would be really tough, so it may not help much as water would preferentially be drawn from the path of least resistance. If you ran the output of one of them to the inlet of the other in series, that would help. To get hot water with minimal delays, you'd probably want to install a hot water recirculation system and insulate as much of the hot and cold return line as you can.

If you don't have a tempering valve on the WH feeding the tub, add one and crank the aquastat up higher. That would be the least work.

 

[Sponsor]

 

[bikeboy]

If the two hot lines are not now connected together, because of the significantly different run lengths, balancing them would be really tough, so it may not help much as water would preferentially be drawn from the path of least resistance. If you ran the output of one of them to the inlet of the other in series, that would help. To get hot water with minimal delays, you'd probably want to install a hot water recirculation system and insulate as much of the hot and cold return line as you can.

If you don't have a tempering valve on the WH feeding the tub, add one and crank the aquastat up higher. That would be the least work.

I've had WH#1 turned up to over 140deg. w/o tempering valve, and still could not reach desired water temp, and top element wouldn't shut off probably cause of incoming cold water. it may work if there was a tempering tank ahead of it. ground water should have been approx. 55 deg. I'd never want to turn up WH above 120deg. Could I install a small circulator pump @ 2nd WH circuit to pump hot water to WH#1 line regulated to tub and mix that way to lessen the path of least resistance from 1st WH ? If not, then I would install it as the former method described.

Thanks for reply'
HR...

 

[Jadnashua]

The aquastat on some residential WH can go to 160 or even higher. Your standby losses will be higher, but you'd never want that temp water coming out of the taps...install a tempering valve and crank the tank up to max and see what happens. 140 will help, but 160 or 180 will help more.

 

[WorthFlorida]

At the 160 degree or higher, the T&P valve will open. It seems everyone in the country has problems filling up these huge spas or tubs in homes with water heaters. We had ours completely removed when we did our bathroom remodel. A larger shower and added two more base cabinets was the result. About the only thing that will work to meet user expectations is a high powered 120 gallon Lochinvar water heater with a tempering valve. Maybe a tankless water heater where the manufacture claims continuous hot water on demand but only if the output can be maintained, all depending on cold water temperatures. A gas or oil fired boiler that produces the domestic hot water may work. 50 gallon or even 80 gallon electric (4500 or 5500 watt) residential water heaters just cannot keep up with these spa tubs. Builders love to install this since people go gaga over them that help sells the home.

 

[Dana]

At the 160 degree or higher, the T&P valve will open. It seems everyone in the country has problems filling up these huge spas or tubs in homes with water heaters. We had ours completely removed when we did our bathroom remodel. A larger shower and added two more base cabinets was the result. About the only thing that will work to meet user expectations is a high powered 120 gallon Lochinvar water heater with a tempering valve. Maybe a tankless water heater where the manufacture claims continuous hot water on demand but only if the output can be maintained, all depending on cold water temperatures. A gas or oil fired boiler that produces the domestic hot water may work. 50 gallon or even 80 gallon electric (4500 or 5500 watt) residential water heaters just cannot keep up with these spa tubs. Builders love to install this since people go gaga over them that help sells the home.

I had some neighbors who installed a spa-tub as part of a master bedroom suite addition, but they didn't upgrade the water heating capacity. To the best of my knowledge in 2 years they never filled it. The people who bought the house next tried to fill it shortly after moving in and couldn't.

The house is heated with an oversized steam boiler, so they were able to install an indirect tank running off the boiler and attain acceptable hot water delivery, but they didn't use the tub very often either during the ~8 years they lived there. (Busy professionals don't have time to fill big tubs and lounge around in them). I don't know if the current owners (a pair of lawyers) use it at all.

Those tubs do look like "the lap of luxury" in brochures though!

 

[Jadnashua]

If your T&P valve opens at 160, something is wrong. It is designed to open at 210-degrees OR 150psi. My guess is that they did not have a working expansion tank orit was too small, and the have a closed system. IOW, the thing should not open because of that temperature. If the ET was defective or undersized, it may reach its limits, and allow the pressure to spike and that caused it to open.

 

[JerryR]

I've had WH#1 turned up to over 140deg. w/o tempering valve, and still could not reach desired water temp, and top element wouldn't shut off probably cause of incoming cold water. it may work if there was a tempering tank ahead of it. ground water should have been approx. 55 deg. I'd never want to turn up WH above 120deg. Could I install a small circulator pump @ 2nd WH circuit to pump hot water to WH#1 line regulated to tub and mix that way to lessen the path of least resistance from 1st WH ? If not, then I would install it as the former method described.

Thanks for reply'
HR...

I had the same issue, but in Florida, with a whirlpool tub in master bathroom. My incoming cold water is 72 degrees. A tempering valve and setting the water heater to 145 degrees more than fixed the issue. I have tempering valve set to 115 degrees. We fill the tub water temp to about 105 degrees. I use a digital thermometer since my grandson is the one who uses that tub the most and I am concerned about not scalding him.

My master bath is 80 feet from the water heater. It takes a full 2 minutes of running hot water before it gets hot in the master bath. I installed a re-circulation pump with an on-demand switch. I push the switch 2 minutes before showering to get hot water to that end of the house. Pushing the switch runs the pump until hot water gets to the master bath then turns off until switch is pushed again.

 

[WorthFlorida]

If your T&P valve opens at 160, something is wrong. It is designed to open at 210-degrees OR 150psi. My guess is that they did not have a working expansion tank orit was too small, and the have a closed system. IOW, the thing should not open because of that temperature. If the ET was defective or undersized, it may reach its limits, and allow the pressure to spike and that caused it to open.

Sorry, you're right. I was thinking 150 degrees. Bummer getting old in retirement.

 

[bikeboy]

I had the same issue, but in Florida, with a whirlpool tub in master bathroom. My incoming cold water is 72 degrees. A tempering valve and setting the water heater to 145 degrees more than fixed the issue. I have tempering valve set to 115 degrees. We fill the tub water temp to about 105 degrees. I use a digital thermometer since my grandson is the one who uses that tub the most and I am concerned about not scalding him.

My master bath is 80 feet from the water heater. It takes a full 2 minutes of running hot water before it gets hot in the master bath. I installed a re-circulation pump with an on-demand switch. I push the switch 2 minutes before showering to get hot water to that end of the house. Pushing the switch runs the pump until hot water gets to the master bath then turns off until switch is pushed again.

Well; since I have two water heaters; What I would like to do is to run a 3/4 hot water line from the far WH to WH for the tub, and install a type of valve that would allow both WH sources to merge into the tub spout. I would need a valve to sense either pressure or flow too get a balance of the two water HTR's flow. I was told I had to balance the flow or hot water takes from the closer WH, and the far WH would not flow. I rather not have a circulator and loop unless it's only option w/o changing the tub's WH. I don't really need instant hot water everywhere.

HR...

 

[Phog]

Respectfully, we've told you the right way to do this multiple times. Run the tanks in series, see above & previous other thread where you asked the same question for exact details on what is needed.