Circulating Hot Water for Freeze Prevention System

[MDSinMI]

Hi folks, new to the forum. Here's an interesting challenge for those so inclined.

I'm embarking on a new project to create a freeze prevention system for my hot water system at my weekend home. The home is never closed for the winter, but due to the fact that there is no basement, the gas hot water heater is in the garage. Normally this has not been much of a problem. I had heat tape on the cold water inlet, and only when the temperature got below 35 in the garage itself against the back wall did the tape kick in (not often). Prior to the tape I'd have one or two freezeups but now since this Polar Vortex is a thing, time for a different approach.

I don't like heat tape. To me electricity and water do not mix. Also had a house fire once caused by one of these so I'm a bit leery of overdoing it with them, and they come with a million warnings. I had a lot of this at the car wash once and eventually all of it failed.

I'm not a professional plumber but was a long-time car wash owner so I had miles of pipe and tubing and did much of the connection and maintenance. I designed, with some assistance, my home driveway's de-icing system, so I am reasonably skilled. This idea came from something I had at the car wash to keep the lines in the attic from freezing..

What I'd like to do for this home is add a small circulator pump in the crawl space to flow water from the hot side of the tank, back to the cold, when the temperature is 35 or below. The tank is kept on vacation setting when away, so will always be at least warm. I'd isolate this mini loop with some stainless check valves (swing style) with a teflon seal. See the drawing. Thus with flowing warm water, my lines would not freeze. I never met a spring valve that would last more than a few years.

I really don't need much flow, so what kind of pump to use? As this is potable water it has to be stainless or bronze, but I don't need much head or capacity. I see all kinds of pumps ranging from $60 to $600 or more many of which look the same. I'd like the pump to be reasonably cheap, under $100 if possible.

The thermostatic control is not an issue, plenty of controls in the $35 range.

So, those who enjoy a challenge--have a look at the drawing. Any suggestions as to kinds of parts, or brand recommendations? Am I missing anything? Suggestions for improvement (besides the obvious shut off and isolation valves)? Thanks and look forward to some ideas!

 

[Diehard]

So may I assume you connect the hot water side to the cold water side at some point within an area above the crawl space that is kept at an above freezing temperature? With a valve of course.
I would assume that you already have those lines, with the freezable areas, insulated.
Do you have any safeguards, such as something to notify you when/if the the system malfunctioned?

 

[frodo]

I do not understand why you do not simply drain the system
water heater included,
when not in use.
then winterize the drains and appliances

 

[MDSinMI]

I do not understand why you do not simply drain the system
water heater included,
when not in use.
then winterize the drains and appliances

Frodo, you completely missed the point.

The house is in use all the time, even in winter. "Winterizing" is something you do when you are away for a very extended period: you do it ONCE at the beginning of the winter, and UNDO it once at the end. Many people in this community do "close their homes" for the winter, and it's an annual ritual of draining the plumbing, filling toilets with antifreeze, etc. But my home, though a second home, is in use all winter. I've been at this home at least a dozen times in the past 90 days. So "winterization" each time I leave is wholly impractical.

But, all it takes is one very cold night, when the outside temps are below zero, and the water still from no use for the pipe to freeze; generally it's only the cold inlet side of the tank.

In 25 years the pipe has only frozen three times, but with these polar vortexes now coming with alarming frequency, it will happen more often.

 

[MDSinMI]

So may I assume you connect the hot water side to the cold water side at some point within an area above the crawl space that is kept at an above freezing temperature? With a valve of course.
I would assume that you already have those lines, with the freezable areas, insulated.
Do you have any safeguards, such as something to notify you when/if the the system malfunctioned?

If you look at the drawing, the connection between hot and cold is with a pump and the flow is guided with check valves. The crawl space is insulated and is never even remotely cold, there is essentially zero chance of that freezing. When we leave the home for any length of time in the winter, the temperature is set to hold at 54 degrees. The thermostat is internet connected and it will message me if it gets disconnected.

It is easy enough to add another control to ensure all is well with any other system.

This home is on well and septic; we always turn the water pump off when we leave. And, it is easy enough to depressureize the system when we leave as well.

My goal is to keep the hot water system going at all times in the winter.

 

[frodo]

,,,

 

[MDSinMI]

You are using the drain of the tank...one issue is everything for this system has to be located in the crawl space, not at the tank...

But, if I read this correctly, you are using a pump OUT of the tank drain, through a "throttle" (I assume this to be a globe valve).

Doesn't look much different that what I have done except the tank drain usage? Or am I missing something?

What kind of pump would you use out of the thousands out there?

 

[Diehard]

If you look at the drawing, the connection between hot and cold is with a pump and the flow is guided with check valves. The crawl space is insulated and is never even remotely cold, there is essentially zero chance of that freezing. When we leave the home for any length of time in the winter, the temperature is set to hold at 54 degrees. The thermostat is internet connected and it will message me if it gets disconnected.

It is easy enough to add another control to ensure all is well with any other system.

This home is on well and septic; we always turn the water pump off when we leave. And, it is easy enough to depressureize the system when we leave as well.

My goal is to keep the hot water system going at all times in the winter.

Okay. I wasn't 100% sure of the details. So the garage area is the only area subject to freezing. And the crawl space is always above freezing. In that case what you have looks good to me.

I would look into a small circulator by Taco or Bell & Gossett.(Very reliable and designed for hot water.) Look at their pump performance curves on their web sites. Being a circulating application and not a pumping application, the only head condition would be the slight friction loss while flowing a minimal amount. So it's probably the smallest one they have. Probably 1/40 HP.(About 20 Watts)

 

[PlumbGate]

No need to reinvent the wheel. The device you want already exists. I added it to my house 2 years ago and LOVE it. I added an additional thermostat mixer btw. You can get them separate to use as many as you need.

https://www.amazon.com/gp/product/B000E78XHG/?tag=skimlinks_replacement-20

 

[Mikey]

What PlumbGate said. I love mine. If you're gadget-obsessed, you could probably wire in a thermostatic switch in place of the timer, or (better, imho) set the pump to be on all the time, and plug it in to your thermostatic switch thingy.

 

[havasu]

I too love mine. No more waiting several minutes for hot water at my bathroom farthest from the water heater.

 

[Diehard]

No need to reinvent the wheel. The device you want already exists. I added it to my house 2 years ago and LOVE it. I added an additional thermostat mixer btw. You can get them separate to use as many as you need.

https://www.amazon.com/gp/product/B000E78XHG/?tag=skimlinks_replacement-20

Not quite right for THIS application.

 

[PlumbGate]

Not quite right for THIS application.

Why not? It looks to be perfect for it. It slowly circulates the hot water through the cold, protecting both the hot and the cold pipes. The only thing is to make sure the thermostatic valve is located where it will protect the pipes that need protecting. What are you seeing that would make this not appropriate?

 

[Diehard]

Well first off, where would you put the sensor valve? In the garage space which is subject to freezing temperatures or in the crawl space?
Keeping in mind that the sensor valve closes when the temperature in the hot water line hits 98º?

Then there's the consideration of the unnecessary features it includes as well as the higher cost.

 

[PlumbGate]

Well first off, where would you put the sensor valve? In the garage space which is subject to freezing temperatures or in the crawl space?
Keeping in mind that the sensor valve closes when the temperature in the hot water line hits 98º?

Then there's the consideration of the unnecessary features it includes as well as the higher cost.

Those pipes go somewhere. It is a simple matter of finding what sink they go to and put the sensor valve under that sink. The only rub would be if the pipe is not paired with a hot like an outdoor hose bib. In that case though it should have the ability to be drained for winterizing.

What unnecessary features does it have? Cost is negligible compared to replacing frozen pipes.

 

[Diehard]

Those pipes go somewhere. It is a simple matter of finding what sink they go to and put the sensor valve under that sink. The only rub would be if the pipe is not paired with a hot like an outdoor hose bib. In that case though it should have the ability to be drained for winterizing.

What unnecessary features does it have? Cost is negligible compared to replacing frozen pipes.

I'm not sure you are totally familiar with the proposed purpose of this application. The OP is just trying to keep piping located in the unheated garage from freezing. Nothing more.

 

[Mikey]

I'm not sure you are totally familiar with the proposed purpose of this application. The OP is just trying to keep piping located in the unheated garage from freezing. Nothing more.

If that's the case, put the sensor on the fixture closest to the WH.

 

[PlumbGate]

I'm not sure you are totally familiar with the proposed purpose of this application. The OP is just trying to keep piping located in the unheated garage from freezing. Nothing more.

Are you familiar with how the Watts device works? It was ready made for this application. I still don't understand why you don't think it would work.

 

[Mikey]

Usually, you place the sensor at the fixture furthest from the WH to ensure hot water at all the intermediate fixtures. In this application, there is a chance that it might not adequately protect the cold-water piping, unless the sensor is very close to the WH.

 

[bbp]

If your getting involved with pumps,elctricity,re-piping etc. Why wouldnt you fix the real issue? Enclose water heater( with adequate make-up air) in an insulated closet with a small section of thermostatically controlled electric baseboard. Put another wi-fi sensor in there and your done.