Smart Hot Water Recirculation DIY

[William Cooley]

Goal is develop smart hot water recirculation system as off-the-shelf products don't meet my needs.

I have two water supply zones. The whole house is on 3/4" except master bathroom shower and jacuzzi tub on 1". Zone are separated just downstream of water heater.. I want to recirculate the 1" zone.

The jacuzzi tub enclosure already has power and plenty of room to add equipment.

I have two ideas:

1) A pump that sits in the jacuzzi enclosure and pumps hot water into cold side. Would be controlled with smart switch (easy). Would need a mechanical, normally-closed valve to shut off crosslink.

2) A wifi-enabled valve to crosslink the hot and cold at the jacuzzi. The pump would be located on the hot water heater (traditional). Smart switches would open the crosslink and then run the pump for a set time.

Any leads on a wifi valve or pump with built-in stop valve? Commercial products are all 3/4".

Open to alternative ideas, too.

Thanks!

 

[wwhitney]

Goal is develop smart hot water recirculation system as off-the-shelf products don't meet my needs.

What's wrong with just sticking a typical under sink on demand recirculation solution under the jacuzzi tub? Trying to clarify the design requirements.

Cheers, Wayne

 

[Sponsor]

 

[William Cooley]

What's wrong with just sticking a typical under sink on demand recirculation solution under the jacuzzi tub? Trying to clarify the design requirements.

Cheers, Wayne

All cross connect valves I've researched are 3/4". I suppose I could make an adapter. I'm looking to make one that is on demand smart. "Alexa, warm up the shower." Valve opens, pump runs. I don't want the waste of a timer system.

 

[wwhitney]

All cross connect valves I've researched are 3/4". I suppose I could make an adapter.

Yeah, if there's something off the shelf that you like and the only issue is you'd prefer 1" connections to 3/4" connections, adapting the size would be a good way to go.

The only possible issue would be how long the pump has to run; from the length of the 1" run, you can figure out the volume of stale hot water you need to move, which with the pump flow rate will tell you how long it has to run. I don't think it would be a big deal if it takes 15 seconds rather than 10 seconds; but if it's important to you, a bigger pump would likely have bigger connections.

Cheers, Wayne

 

[Jeff H Young]

bigger than 3/4 ? why? just put an ordinary recirc pump and all your smart stuff to make it work its just pumping hot water into your cold line for a minute.

 

[William Cooley]

bigger than 3/4 ? why? just put an ordinary recirc pump and all your smart stuff to make it work its just pumping hot water into your cold line for a minute.

More concerned with impact of choking 1" jacuzzi supply line to 3/4" if using existing products. Wouldn't it slow time to fill massive jacuzzi tub?

 

[William Cooley]

Thanks all for the help. It takes 4 gallons to flush the 1" hot water line until hot water is flowing. The difference in time to pump isn't the concern with 3/4" vs 1". The time to fill the 60 gallon jacuzzi tub is. Using 3/4" products would, I assume, significantly slow the flow rate.

The line coming out of the water heater is 3/4" and then is transitions to 1" for the long run. I believe the purpose is to reduce friction loss for the long run.

 

[wwhitney]

More concerned with impact of choking 1" jacuzzi supply line to 3/4" if using existing products. Wouldn't it slow time to fill massive jacuzzi tub?

But you wouldn't be changing the size of the piping to the tub. If there's a 1" hot line and a 1" cold line, you'd cut a 1" x 1" x 3/4" tee into each line, and install the circulation pump between the two 3/4" connections.

Cheers, Wayne

 

[Jeff H Young]

But you wouldn't be changing the size of the piping to the tub. If there's a 1" hot line and a 1" cold line, you'd cut a 1" x 1" x 3/4" tee into each line, and install the circulation pump between the two 3/4" connections.

Cheers, Wayne

exactly even 1/2 inch makes no difference to the tub just like Wayne says it's still a 1 inch line. so like I said no difference unless there is another issue

 

[William Cooley]

The solution you outline would work great... no change to tub flow rate and use of existing parts. Looks like a Taco Geniue pump has a built in stop valve to close off the cross connect.

https://www.tacocomfort.com/product/taco-genie/

Also, the taco can be set to turn on when power is applied. This would allow me to power it with a smart switch and enable smart control.

Thanks!

 

[Jeff H Young]

good luck I don't have a lot of answers but don't see a problem so far