Nothing in life is ever cut and dry. There are always going to be some advantages and disadvantages.
Take a hot water recirculation pump.
You want instant hot water when you turn on the faucet. At the same time, you may feel like it saves water and money, but does it really?
How much do the best ones cost? Is the installation expensive?
You’ve got questions and I’ve got the answers.
In this article I will highlight everything you need to know about recirculation pumps. There are several options to getting instant hot water so you need to understand which one will fit your needs best and if it is even worth it to buy one.
Read More!
If you need to see in depth reviews of the best pumps then be sure to check out the detailed buyer guide for recirculating pumps. If you don’t have time to read it I listed the best models right below.
Advantages and Disadvantages
Pros
- Instant hot water to any fixture
- Wastes less water since there is no wait
- Easy to DIY install and operate
- Can be found easily on Amazon at great prices
- Work with timers to not run when there is nobody home
- Small and compact and fit under a sink
Cons
- Some models make the cold water lukewarm
- Require a power source near the installation
- Low output in cold climates
- If you require hot water for a time when the timer is not set, you won’t have instant hot water
How does a hot water recirculation pump work?
Think about how things go when you don’t have a pump.
Your tank heats your water to the temperature that you like. But, it doesn’t pump the water to your faucet until you turn it on. So, that water sitting in your pipes from the tank to your faucet ends up cooling to the ambient temperature.
Now, you turn on the hot water and wait for the heated water to finally arrive. In some cases over a minute, which then washes all that water down the drain.
With a recirculation pump, the idea is that there is a flow of continuous hot water through the pipe so there is no wait for hot water. It is already hot at the point of arrival.
How does this work? Different units work differently, but the idea is that the pump keeps the hot water moving through the pipe where it either ends up back to the boiler with a dedicated line or there is a system in which the hot water runs through the cold water pipes.
I’ll go over the way different ones work in a bit.
Do recirculating pumps save money?
This isn’t an easy question to answer. They definitely can save money, but it depends on what kind of pump and how it is used.
How much water do we waste by waiting for the hot water? Let’s say it takes a minute for your water to arrive at the tap or shower. If you are using low flow fixtures, you just dumped at least 1.5 gallons down the drain with the shower and 2 gallons at the kitchen sink.
Add that up over a year and you can see how much water is wasted.
So, if you waste say, 10 gallons of water per day, that adds up to at least 3,650 to 5,000 gallons per year. And that is a very conservative estimate.
But, that only adds up to about 8 or 12 dollars per year.
So, they won’t save you much money unless you have a huge family, in an enormous house with the furthest fixture more than 100 feet from the water source.
If you just hate the thought of wasting water and not counting the cost, then the good news is that it does save water.
What about the electricity to run the pump?
This is where what kind of pump you get really matters. If you have the traditional one that is basically pumping water all the time, then you are actually costing yourself money in the long run. They don’t typically use a lot of electricity as they are very small pumps, but they certainly are not saving money.
The basic answer is no they won’t save you money.
I still think they are worth it, but first, let’s talk about the different kinds because this will make a big difference.
Types of recirculating pumps
There are essentially two different kinds of recirculation pumps that you will likely to be looking into.
Traditional Full Recirculating and Under Sink Recirculating Pump Comfort System.
Both have their pros and cons, but understanding each of them will help you decide which one is going to be right for you.
Read More!
Do you have a tankless water heater or are thinking of getting one? Then read this article about tankless water heaters and recirculating pumps to learn more about it!
Traditional Full Recirculating
For many years this is what you likely would have gotten if you were looking to get instant hot water to your fixtures. In fact, many hotels around the world use this system for the convenience and comfort of their guests.
This pump be placed over the boiler will circulate the hot water from the tank to your faucet. At the furthest point from the boiler, you’ll need a dedicated hot water line that runs back to the tank, creating a perfect hot water loop.
Now, that doesn’t mean that you’ll have hot water circulating 24 hours a day through that line. Almost all recirculating pumps these days will have a timer on it so it only starts the recirculating at the hours when you’re likely to need the instant hot water.
What makes this a not so attractive option for people is that it requires some additional plumbing to bring that loop together. You’ll need a plumber to run a considerable length of pipe and hook everything up. This can add a lot to the installation costs.
Under Sink Recirculating Pump Comfort System
This is the most likely option that many of you will be looking at. In fact, from this point on I will only be referring to this type of pump as the other is not a great option for most people.
The way this one works is that the pump is installed under your skin, or at least close to the point of use. Instead of needing a dedicated line that loops back to the boiler, this one has a sort of connector that runs between the hot and cold water lines at the outlet. It has a toggle that will open up when the pump is running that allows the hot water to pass through to the cold water line when the faucet is not open. Then the water cycles back to the boiler through the cold water line.
These types all work on timers, too so it is only on when you are home so it isn’t pumping water through the lines when nobody needs it.
The downside to this version is that since hot water is entering the cold water line, then when you want cold water, you have to let the water run a bit to flush out the warm water.
Check It Out
Watch out for units that have the sensor valve inside the pump. If it fails you need to buy a whole new pump. Other models like this one from Watts have it outside so it can be quickly and easily replaced.
Tankless Water Heaters with Recirculating Pump
A sort of third option is to have a tankless water heater that comes preinstalled with a recirculating pump or is at least ready for one to be added.
If you aren’t familiar with a tankless water heater you can read up on the pros and cons of owning one to see if it is right for you.
This is a great option to have as you are not only heating water only when you need it, but it provides endless hot water that arrives at your preferred temperature instantly.
For many people having a tank boiler system is grossly inefficient and would rather have a tankless that provides endless hot water. One of the downsides is the wait for the water to heat which is solved by the recirculation pump.
They are not a great idea for everybody so make sure you click the link I provided to the article and read it carefully before deciding to go for a tankless.
Installation Costs
How much does it cost to install a recirculation pump? It can end up costing as low as zero dollars if you get an under sink recirculating pump and install it yourself.
This is a big reason why I suggest this type of pump over the traditional over boiler ones that require a plumber to run a dedicated line. Unless you can do that yourself it can cost quite a bit to hire a plumber. And even if you do it yourself, you are going to have to pay for a long length of piping and material.
An under sink one can be installed in a matter of minutes. The only thing you may need to pay for is a power source if you don’t have any outlet near your point of use.
Here is a video to show just how easy it is to install.
The unit you get will likely contain all the hoses and connectors so you won’t be out of pocket by needing to buy all that stuff separately.
Should you buy a recirculating pump system?
If you are like me, then you hate the thought of wasting water.
So, even if you don’t really need the comfort of having instantaneous hot water, the idea that you aren’t dumping water needlessly down the drain is reason enough for buying a recirculating pump.
For everybody else who needs some creature comforts, then having hot water as soon as you open a fixture is the height of comfort and once you have it will never want to go back to washing hands in cold water to avoid wasting water.
No, they won’t really save you any money in the short or long term. And, they do need to be put on a timer to keep them from running all day and night. Which can be inconvenient when you want hot water at a not predetermined time.
The cost of a recirculation pump is not that much and installation is easy enough to do it yourself, so it is an easily afforded luxury that at the same time will make your house less wasteful of our precious natural resource.
Do you have any questions about these pumps or any other water system for your home?
Let me know by dropping a comment in the box below. I love getting questions and comments and am here to help!
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Building a new house….originally planned on a tankless water heater (without a pump) but the plumber had already piped for use of a recirculating pump (Noritz 1112-DV-NG) before we realized this was the case. However, the tankless heater unit isn’t yet installed and he will credit us with the cost for plumbing for the recirculating pump if we decide we’ don’t want/need it. He recommends a pump.
Maximum distance of any water line in our house is about 40 feet. There will be 2 showers, 3 toilets, 4 sinks, and a dishwasher. In addition, it is our common habit to be away for days at a time on a regular basis and when we do, we like to shut off the household water supply just so no disasters happen in the form of leaks while we’re not around. (We are overly-cautious based on having just such a disaster in a previous house where the entire floor had to be removed to repair damage). If we are shutting off the water supply would we then have to be re-programming the pump every single time so that it would not burn out by operating without a water supply?
Have to decide whether we want the recirculating pump within the next few days, so scrambling to know what’s best. Have read all the “pros and cons” sites about recirculating pumps, but of course there’s no clear answer; new advice would be appreciated!
Hi David. Usually, the recirculating pumps have a timer that is like a dial. It almost looks like one of those combination locks for bikes in a way. So, you turn and press the times times like little buttons. They aren’t digital, it’s very analog. In other words, when you set it, it will stay that way even if you lose power. One thing I can’t figure out is why the plumber is recommending not going with the tankless if you have the recirculating pump. They do 2 different things. Unless he is concerned that the pump won’t work with the tankless as not all of them do. Anyway, let me know how you make out. Good luck!
Hi Nick: Aome confusion here ….We WILl have a tankless system and the plumber IS recommending use of a pump. What we are trying to decide is whether or not to hook up the pump or to just leave the recirculating piping unattached and opt for a tankless unit that does not incorporate a pump.
Hi David, yes, I see the confusion here. So, again forgive me if I am misunderstanding, but I think what you are saying is that the plumber already set up a loop with a dedicated return line and you want to know if it is worth it to have a tankless with a pump. I am not familiar with how the Noritz recirculating pump works, though as I have never seen one.
If I were you I would have both. Since your fixture is a bit far from the source of your hot water, you will inevitably waste water while waiting for the hot water to reach the faucet. If the loop is already made, then this is actually ideal. With some under-sink systems, you end up having your cold water feel too warm. This is not the case when you have a dedicated return. The reason that the comfort systems are popular is that you don’t need a plumber to install them. You obviously do not have that problem. I hope this helps.
You don’t talk about the extra cost of heating the water as it recirculates. I am curious if you have any idea how many BTU’s or Watts are used to keep the water hot in a 100 ft recirculating loop where the return line is the cold water line.. PEX or copper would be fine. I can convert between the 2.
Do these pumps run all the time when the timer is on or is there a sensor that shuts it off when it gets to temp and then turns back on when it gets down to another temp (like a furnace thermostat). The real question I am trying to answer. If I have a 100 gallon tank at 130 deg, turn the water heater off and then turn the pump on, how fast will the temperature drop in the hot water tank. Assume the water tank has infinite insulation for this question.
I have spent several hrs on line trying to find enough info to calculate this myself and don’t feel like I have quite figured it out yet.
Hi Dave
That’s a really good question and to be honest, I am not sure myself how many BTU it would use. To answer you rother question, though, when you have the timer on it does have a thermostat. At least the ones I linked to on Amazon do. So when the timer is on it only recirculates until the temperature is reached. Then it will shut off until the temperature dips and on it comes again. When the timer is off, it doesn’t circulate at all so you only get the hot water to the fixture from the heater. Going 100 feet I would think it would take at least 30 seconds to reach the furthest fixture. I’m not sure I understand what you mean about turning the heater off. Do you mean how long does it take for the water in the line to cool when you shut the faucet off? If you shut the heater off then the recirculating pump will only be able to circulate the water whatever temperature it may be. How long that stays hot is dependent on your tank. As you said it is insulated so it should stay hot for a few hours I would think. Though, with the water circulating it will cool faster than if it is in the tank. I know this answer doesn’t help, but there are a lot of hypotheticals.
Thanks for the interesting question!
Nick
Thanks for the comments. Perhaps I will try another question. If I start with 100 deg f water at one end of a 1/2 Pex line, what will the temperature be after running 100 ft. The room temperature is 70 deg f. I found this info
q = k A dT / s
q = heat transferred per unit time (W, Btu/hr)
A = heat transfer area (m2, ft2)
k = thermal conductivity of the material (W/m.K or W/m oC, Btu/(hr oF ft2/ft))
dT = temperature difference across the material (K or oC, oF)
s = material thickness (m, ft)
I used these numbers( BTU version)
k 3
A 0.520833333
dT 30
s 0.005208333
Pex perimeter 1.831666667
Pipe length 100
I get 9000 BTU/hr
Or ~2400 watts
So I think this says to keep my hot water faucet hot 24/7 would require the equivalent of a 2400 Watt heater on 24 hrs a day
My friend, that is seriously impressive! Math was never my strong suit so there is no way I would have been able to come up with formula to work that out. Kudos to you!
As far as the energy needed to heat your water 24/7, you can see how horribly wasteful a recirculating pump is if you don’t use a timer. It is definitely not something I recommend. Just as I don’t recommend taking 30 minutes showers with a tankless water heater just because you have endless hot water. It’s nice to have when you need more hot water than a tank could provide, but it shouldn’t be abused.
Anyway, thanks for that insight. Great work.
Good morning Nick, I appreciate all your info! I will be doing a replumb using Uponor Wirsbo on a 1600 sq ft ranch style home, the longest run is to the 2 baths and is about 40ft..Of course a return line at this point is a good option. I will be using manifolds for each area of the house, one for kitchen area, laundry, hose bibs,(very close to the water heater) and one for the baths. ? If I use a Watts 500800 without a return line how long does it take to purge (the warmed up) cold water line? ?If I use a flow through manifold on the hot to the furthest hot water line can that be my dedicated return line back to the water heater? Lastly, can I T the return line at the cold in on the water heater? Thanks for your help and any additional input would be great.
Hi Lloyd!
I think I understand what you are saying if you mean the manifold being the valve on the comfort system under the sink. So, yes that line through to the furthest point is going to be return line back to the heater after it’s already passed through the manifold into the cold side. Now, how long to get the warmed cold water to flow through so you get cold water is tricky to answer. It doesn’t really matter how far it is from the heater. The problem is that while it is pumping, the hot water is always going to bleed into the cold water side. You may not ever get truly cold water at that fixture. If it’s a bathroom maybe it doesn’t matter. At the kitchen sink, if you are drinking and expect cold water, then that could be disappointing. And as far as the last question, I am not sure, but it is an interesting point. I’m honestly not sure if that will work since you will be flowing the water back upon itself. There might be a way, and honestly, I am not somebody who can do plumbing while winging it. I need to follow instructions to make sure I do it correctly and have trouble visualizing an impromptu type of solution. I’m not a pro by any means so that is outside my wheelhouse so to speak.
Thanks for reaching out and I hope that helps you somewhat. Also, I think you’ll like that Uponor Wirsbo assuming you are doing a PEX set up. It will make further plumbing much simpler on yourself.
Good luck
Nick
Know anything about the WaterQuick – Standard” recirculating system? I’m reading about it now and sounds to be very cost effective and easy to install. Parts < $400 as well.
Hi Ron
I almost put the Waterquick on the list because of how fast it heats the water. It has an ingenious system to make sure there is always hot water without it flowing constantly. That said, one of the downsides is that it doesn’t have a timer. So, some people may see a higher electric bill because of that. I think it depends on how you use it. If you are home a lot and often need hot water then I say this is a good one to get. If you only need hot water at certain times of the day, then one with a timer is better. It seems like not being tied down with a timer is a nice selling point besides the fact that it does get water to the fixture faster than others. If your fixture is further than say, 40 feet then you’ll see much faster hot water than with other units.
I installed a Watt 500800 pump for my brother-in-law and he said it works great. It was programmed to pump around 6 hrs a day and he said his gas bill went up quite a bit. I have not seen anywhere where they say your gas consumption will go up. What do you know about this? It is great to have hot water but at what cost.
Hi Charles. Yes, that is very odd that his gas bill would go up. Does he have it installed on a tankless water heater or traditional tank? If it is on a tankless and it is not caused by higher gas rates in his area, then he might want to install a pressure tank so the tankless isn’t running for those 6 hours. If he has a tank, then that is really a mystery as a tank is turning off and on throughout the day anyway even without the pump. Thinking more about it, I wonder what the temperature of the incoming water is to his house and that it might be the added BTU required to get the temperature of the water up to where he has it set.
I’m not really sure what the answer is here but it is odd.
Nick
Hello
I have a circulating pump installed on top of my heater but it does not have a timer. The voltage in my location is 230.
Are there mechanical timers that i can install on the wiring of the pump ? I say mechanical because i am plagued with frequent power outages and also 230 volt timers may be hard to come by.
Kind regards
Hi Manfred
I am sorry to say that I don’t know of any that you can hard wire to the pump in that way. I will put this up in hopes that some other readers may have an idea of how to do this.
Good luck
Nick
We had a circulating pump failure resulting in water damage. An emergency plumber called out to find and stop the leak temporarily and quoted us $2k for labor and parts to bring in new pump and valves next week. After running across this blog I’m wondering if we are being taken for a ride, and frankly wondering if a pump is even necessary. Seems like more of a convenience than anything else. I have 2 hot water heaters aged about 8 years that I plan to replace this month (as this disaster has made me realize I should be more proactive than reactive with this stuff!) so looking at A LOT of $$. Plumber told us parts were $1700.. does this sound off? Further told us that our current busted pump doesn’t have a timer on it but made it sound like the replacement won’t either… he recommended we buy a timer and attach it to the new unit. If these pumps are offered with a timer why wouldn’t they just install that? Are there conflicting viewpoints re pumps with built-in timers vs those without? Lastly, if plumber is willing to install a pump that I source myself, do you have any suggestions on brand/make? Home is 5000sf with 2 water heaters, 4 bathrooms. Thanks!
Hi Michelle. Your plumber is definitely inflating things but is not completely off. You’re right that a circulating pump is really about convenience and isn’t needed except in certain situations. If you don’t mind waiting for hot water at the faucet then you really don’t need one. And as far as the timer this is where the plumber is way off. All you need to do is buy a pump with a timer. It doesn’t need to be any more complicated than that. Now, you can install this yourself if you go with under sink models like this Grundfos model that even has a digital timer with it. I would go with a couple of those and skip the plumber.
Hope that helps, Nick