Hot Water Recirculating Pump - Pump needed?

[SabrToothSqrl]

After 12 years of turning on the shower, brushing my teeth, then getting in the shower a while later, because it takes an eternity to get hot water in the master bath... (The builder placed the water heater about 10 feet short of literally as far as it could be from the master bath).
I thought this was normal, since I'd never heard of anything else. But I was tired of it. Started doing some research.

(Shower is on 2nd floor, heater in basement)

I installed this:

https://www.lowes.com/pd/Watts-HRWS-Universal-Steel-Water-Heater-Recirculating-Pump/3135231

And, within a day noticed:

1. it works. (water is warm within 10 seconds at shower, and you can get in within 15 seconds).
2. I don't think I need the water pump part.

How do I know?

Well, I set the pump to 4PM to 11PM to start with.

Took a shower at about 10AM yesterday and today, and had hot water within seconds.

The water seems to be circulating based only on heat difference.
I can tell since the cold line is warm under the sink where I installed it.

I didn't get to time, time to warm, before the under sink valve, but I can turn that off and time it in the AM for comparison (it was at LEAST 45+ seconds if not a full min).

Anyway, I've unplugged the pump to 100% confirm it works fine without it, I don't know if I'll remove it to reduce leak points or not yet. The whole casing is metal and would leak tons of heat into my basement. So that's a negative. You can buy just the valve alone:

Amazon.com

I installed the valve first, but then installed the pump same day.
Wish I had known having just the valve could have worked.
(Might not work for everyone).

I do wonder if I'll get hot water faster w/the the pump - 10 seconds seems so much nicer than the minute it was before.

I also am concerned that in summer, when the house/basement are warmer, the 'automatic' circulation would not be as effective.

so, I think I'll leave the pump in place, for now. unplugged.
I would like to wrap it in insulation. I'm an efficiency nerd when it saves my wallet!

 

[petit_bateau]

After 12 years of turning on the shower, brushing my teeth, then getting in the shower a while later, because it takes an eternity to get hot water in the master bath... (The builder placed the water heater about 10 feet short of literally as far as it could be from the master bath).
I thought this was normal, since I'd never heard of anything else. But I was tired of it. Started doing some research.

(Shower is on 2nd floor, heater in basement)

I installed this:

https://www.lowes.com/pd/Watts-HRWS-Universal-Steel-Water-Heater-Recirculating-Pump/3135231

And, within a day noticed:

1. it works. (water is warm within 10 seconds at shower, and you can get in within 15 seconds).
2. I don't think I need the water pump part.

How do I know?

Well, I set the pump to 4PM to 11PM to start with.

Took a shower at about 10AM yesterday and today, and had hot water within seconds.

The water seems to be circulating based only on heat difference.
I can tell since the cold line is warm under the sink where I installed it.

I didn't get to time, time to warm, before the under sink valve, but I can turn that off and time it in the AM for comparison (it was at LEAST 45+ seconds if not a full min).

Anyway, I've unplugged the pump to 100% confirm it works fine without it, I don't know if I'll remove it to reduce leak points or not yet. The whole casing is metal and would leak tons of heat into my basement. So that's a negative. You can buy just the valve alone:

Amazon.com

I installed the valve first, but then installed the pump same day.
Wish I had known having just the valve could have worked.
(Might not work for everyone).

I do wonder if I'll get hot water faster w/the the pump - 10 seconds seems so much nicer than the minute it was before.

I also am concerned that in summer, when the house/basement are warmer, the 'automatic' circulation would not be as effective.

so, I think I'll leave the pump in place, for now. unplugged.
I would like to wrap it in insulation. I'm an efficiency nerd when it saves my wallet!

If it helps, these things are often called "bronze loops"

"Installations which have a long pipe run to the final hot water tap or shower may suffer from excessive draw-off (and therefore wastage) of water that has cooled in the pipe, before the required hot water is available. A secondary hot water circuit with circulating pump will overcome the problem, ensuring that no water is wasted, because hot water is immediately available even from the tap furthest from the storage point.

A standard pump would fail prematurely in this application; the pump body is bronze so that it does not react with the regularly replenished (and therefore oxygenated) water. The bronze pump should be installed in a return loop added to the hot water supply plumbing after the furthest tap in the circuit. The return tapping should be into the upper third of the hot water storage tank (in order to avoid de-stratifying the tank contents)."

Bronze Recirc Pump – Corgi Controls

 

[nwdiver]

Keep an eye on how much more energy your water heater is using. Having a thermo-syphon might be a mixed blessing since you'd need a valve to shut it off when you don't need to keep your water circulating.

A friend of mine was trying to figure out why their new house was using so much energy. One cause they discovered was the water recirc pump. It more than doubled the amount of energy their water heating was using.

 

[David_Cary]

Yeah - if it is working without the pump, then the energy lose is going on 24 hours a day. And can be more work to shut off for vacations.
The pump energy use is pretty small. The heat loss is enormous.
Obviously, situations can vary a lot but I have seen $100 a month in extreme situations. Yours is not likely that bad.
The primary factor is your method of heating the water. If you have a condensing NG - pretty rare but on happens on systems that tied into a hot water house heating system - and it is winter, the issue is negligible because you are heating the house anyway.
If it is electric resistance in modest electricity rate PA - then $50 a month is best guess. Insulation will help but usually you can't get to most of the pipe. NG - maybe $20; Heat pump maybe $15. The issue with things like heat pumps and NG to a lesser extent is the added wear on the system. If you are losing more heat than a tank typically loses (it was 10X on my partially insulated loop)- then the heater is cycling more often.
I had an energy monitor on mine for many years and it was a solar tank. When the solar wasn't storing much, I could tell when the pump was running based on the 4.5 kw spikes every hour. Mine had a timer as all do - but all dumb timers occassionally are issues - power outages, DST. Once I got it on a smart timer, it was better.
For me, in the summer, most of the time I was not using any electricity for hot water even with the pump. It was heating the house some which necessitated more a/c but that was pretty negligible.
Energy costs have to rise to pay for new infrastructure/renewable gen/storage. Efficiency always matters.
Have you noticed your cold water isn't that cold? Maybe more of a summer time irritation. That looks to be a system where it returns via your cold water line which means it has to warm that line.

 

[SabrToothSqrl]

The water heater is a heat pump model. The wasted heat, heats the house in winter, so, while a heat loss, I'm not sure it's going to make a significant impact. I now have hot water at 10 seconds at the farthest run vs. the original 40 seconds (just measured this AM with pump unplugged and valve shut off). the 50 gal heat pump one actually feeds a 50 gallon propane one, which barely runs since it just keeps it hot. the heat pump one does a good 90%+ of the work. (It's heat pump only mode).

I have insulated all the lines (hot and cold) in my basement that I can reach. I'd love to do the whole house, but not practical w/the drywall in place.

The heat before was wasted as well as it sat in the pipe until cool. Then more waste dumping all that water.
You could maybe math out the loss, but meh. Nothing is perfect.

Yes, the return line is the cold line - I've never really needed super cold water, but if you give it just a sec, it becomes cold again very fast. I would have perfered a dedicated return, but with the drywall in place - that ain't happening.

This thing is a game changer for us. Washing my hands now, even on the first floor bathroom went from turn on hot and wait an eternity, to turn on hot and have water warm enough to wash my hands just fine, almost instantly.

I was on the fence for a while for this purchase. Was kinda skeptical.
Took me a bit to grasp the whole thermo-one-way-valve situation, and using the cold as a return.

Anyway, if you have to wait an eternity for hot water. I certainly suggest one of these things!

Current plan is leave the recirc pump unplugged and play it by ear. If the 'automatic' part of the pumping of water stops for some reason, I will reevaluate. If it works fine without it, I'm tempted to remove it, but that's more work, and I can't really return it ethically at this point.

as always, your range my vary.

 

[SabrToothSqrl]

after additional consideration, the pump is already installed, so it's now back plugged in, and 'on' 4-11PM for now. I'll time a hot water to shower in the AM, and again at 7PM or so.

 

[wwu123]

When we bought our house 20 years ago, some previous owner had installed a gravity recirculating loop, which does not rely on a pump. You ended up with one because your water heater is in the basement and your cold return line is below the level of the fixtures, and is probably returning back into the water heater from the bottom drain outlet. We did rip out the return loop years ago when we installed a gas tankless water heater - needed a minimum 0.5 gpm flow to trigger the tankless burner, so not really compatible with a passive loop, nor did we want the heat losses.

IIRC, the gravity loop did not lose as much energy as one might think. The passive circulation moves much more slowly than using an electric pump, and I recall it was warm not hot initially at the taps, though plenty warm enough for a shower until use brings the actual hot water to the tap. Insulating the loop will not only reduce the heat losses from the circulation, but I think it will slow down the gravity circulation since it reduces the temperature gradient that enables the circulating flow. You might find it actually uses less energy to have a passive loop 24x7, than an active loop from 4-11 pm - the latter not only uses electricity for the pump, but it is circulating a larger amount of water at a hotter temperature, significantly increasing the heat losses around the entire loop.

 

[SabrToothSqrl]

Ass an added bonus: warm water in the 'cold' line results in a fairly nice bidet experience. lol

 

[strider]

We have wrestled with this. Our house came with a dedicated return line, a high-speed pump that was running 24x7, and a resistance electric water heater. I tried leaving the pump off but we would waste gallons of water in the Master waiting for warm water. So we switched to a heat pump water heater and a much slower pump on a timer. I think that gives us a good balance between wasting electricity and wasting water.

 

[SabrToothSqrl]

Update: love this thing. Timer is now set to OFF only 11PM - 7PM. On rest of time. Love it. Worth every penny. Any faucet now has hot water within seconds.

anyone thinking about one. get it.