Grundfos Comfort System

[DavidNJ]

This his a hot water circulation pump. Sensing water temps in the hot water pipes, it recirculates the water to the water tank, ensuring "instant" hot water at the faucet. They say it can save 16,000 gallons/year residentially.

http://www.grundfos.us/web/HomeUs.nsf/Webopslag/PAVA-56TMVA

Do other firms make this? Is it commonly used?

[belliott]

The pump you provided the link for appears to be a used to retrofit a system that did not a have a pump system install during construction. I've never installed one, but I've seen several and they seem to work quite well.

Most all the pump manufactures offer something similar. I know Bell & Gossett as well as Taco do. I recently picked up a Laing that has a built in thermostat.

For years we have neen installing pumps that ran 24/7 for hot water recirc systems. The pumps that have the timer are more energy efficent, since the pump can be programmed to only operate during peak usage times.

I like the idea of the thermostat control pumps, they have been availible for larger scale commercial pumps for a while. I have one of the temp control Laing pumps on my truck, but I have not had the opportunity to install one yet.

[DavidNJ]

Thanks for the info.

The new construction kits appear to use a dedicated hot water return line with either a timer or temperature sensor initiating operation. The retrofit kits use the the cold water line for return with a valve under the sinks and a timer only.

What prevents a retrofit hot water recirculation pump from operating when there is hot water demand at the facet? Is having a dedicated recirculation line preferable enough to have the return line 5-10 feet from the faucet?

When there are branches, how does the system recirculates both branches; that it doesn't just service one branch or if a temperature sensor is used it doesn't turn off when the first branch reaches temperature?

It was interesting to note that the top of the line Laing unit had an ECM motor: "as little as 10 watts".

[belliott]

I'm not a big fan of the retrofit pumps, If the system is on a crawlspace or basement you are much better off the add a dedicated return and do it right.

The place the retrofit pumps shine is on a slab system, they are not perfect but they do improve the time it takes to get hot water to some fixtures. A dedicated system will always better, but is generally cost prohibitive once a slab home has been built. The retrofit kits where the pump is installed at the W/H are superior to the systems that have the pump mounted under the sink.

On the Grundfos system

When there is a demand for hot water at a faucet and the pump is operating, the valve under the sink closes. In fact once the water temp is 98 degrees the valve closes. This is what makes these systems operate like a thermostat controlled system

The comfort valve that Grundfos uses under the sink has check valves in it to prevent cold water from being pulled into the hot water lines while running hot water.

If you have muiltiple branches in the home you just add more valves under sinks and use the single pump. From what I understand a total of 7 comfort valves can be installed.

Here is a link comparing the Watts Premier system to a on-demand push button system. The Watts system is a Grundfos system with diffrent paint and stickers. Other companies make similar pumps.

Watts comparison link:
http://ezinearticles.com/?Comparing-the-Watts-Premier-Recirculating-Pump-to-the-Metlund-DMand-System&id=2309248

Watts Premier :
https://www.wattspremier.com/products.php?product=Instant-Hot-Water-Recirculating-System

Hope this helps

[flange]

have sold a bunch of those for light commercial applications and a few homes. they worked well in all cases. retrofit installed is a bit pricey, but keeps tenants in office spaces happy. had one where thet waited an average of seven minutes before for hot water, zero minutes after install.

[DavidNJ]

have sold a bunch of those for light commercial applications and a few homes. they worked well in all cases. retrofit installed is a bit pricey, but keeps tenants in office spaces happy. had one where thet waited an average of seven minutes before for hot water, zero minutes after install.

Did the retrofits use the cold water lines or a dedicated return line as belliot indicated?

I'm still quite confused how it arbitrates the use of the cold water line in retrofit applications. Also, how it insures all lines participate in the circulation and not just those with the lowest head.

Does anyone make one integrated with the hot water valve that recirculates on demand until an adequate water temp is reached? Sort of an automatic demand button rather than a timer or just a temp sensor that may run when hot water flow isn't needed.

[belliott]

Does anyone make one integrated with the hot water valve that recirculates on demand until an adequate water temp is reached? Sort of an automatic demand button rather than a timer or just a temp sensor that may run when hot water flow isn't needed.

Yes, just about every pump manufacturer offers a pump that can be installed with a demand button. But who wants to push a button every time they go to the sink?

If you want something really cool. Install a " on-demand" pump with a motion sensor.

Taco offers one.

http://www.accentshopping.com/product.asp?P_ID=154019#tabtop

[DavidNJ]

Yes, just about every pump manufacturer offers a pump that can be installed with a demand button. But who wants to push a button every time they go to the sink?

If you want something really cool. Install a " on-demand" pump with a motion sensor.

Taco offers one.

http://www.accentshopping.com/product.asp?P_ID=154019#tabtop


The Taco has both a motion sensor and remote control available; press the button in bed on your way to the bathroom. This problem has been considered.

The ones that work on timers or temp sensors independent of demand apparently use some water heating that is unneeded. Are there any analyzes of those values. The early referenced link comparing an on-demand pump vs. the background pump used that as its main argument.

What I was thinking of is a on-demand system activated by a request for hot water when the hot water temp was too low. It would function as running the water does now, but would recirculate the water instead.

In our house, the first floor faucets can easily have return lines added. When an attic heating unit, AHU or furnace, tbd, is added, return lines could be added to the second floor for just a moderate extra cost.

[genduct]

Seems like if the return water temp KEEPS the hot water pipes filled with hot water without pipe insulation that means greater standby losses vs the extra water use.
I have heard of a simple system that allows you to activate a small bypass pump when you use your bathroom that hit as you go in and that way it is operator determined with no stand by loss that seems more sensible for retrofit

[skippedover]

I'd love to answer but I don't know what DavidNJ is all about. He'st got over 900 posts to this site, gleaning an awful lot of information, yet he refuses to become a pro member. I'm not bashing, I just don't understand. If a person is not in the trades, how is it he loiters around here daily, making all kinds of posts and doesn't qualify as a pro? So, no answer till I get an answer. Sorry.

[DanW13]

I'd love to answer but I don't know what DavidNJ is all about. He'st got over 900 posts to this site, gleaning an awful lot of information, yet he refuses to become a pro member. I'm not bashing, I just don't understand. If a person is not in the trades, how is it he loiters around here daily, making all kinds of posts and doesn't qualify as a pro? So, no answer till I get an answer. Sorry.

What's the difference if he's a Member or just a person who knows or has personal experience on most everything the "Pros" here know. Just because your a Member doesn't necessarily mean you know more than a person who is not a Pro Member does it ? I have posted many times herein on many different subjects thur out the time I have been a member of this site and have never been called out by anyone nor have I seen others call out any non member prior to today.

There is such a thing as a Jack of all trades even though a person isn't a licensed tech in anyone trade, we are home owners, maintenance men/women or people who just might do alot of reader or have first hand experience on many different situation or have used purchased many different mechanical parts or units for our homes and family members homes as well as Friends thru out the years. If a person doesn't have a License does that automatically mean the person doesn't know anything ?

[commerce48]

I'd love to answer but I don't know what DavidNJ is all about. He'st got over 900 posts to this site, gleaning an awful lot of information, yet he refuses to become a pro member. I'm not bashing, I just don't understand. If a person is not in the trades, how is it he loiters around here daily, making all kinds of posts and doesn't qualify as a pro? So, no answer till I get an answer. Sorry.

I don't think he "refuses" to become a pro member - he would probably welcome access to the more technical forums. But he doesn't qualify - he is not in the trade.

[skippedover]

I don't think he "refuses" to become a pro member - he would probably welcome access to the more technical forums. But he doesn't qualify - he is not in the trade.

Well from my perspective, if a person has the need for the volume of knowledge he's constantly debating, then he's either qualified to be in the trade or he's using the information for some other purpose. Personally, I'm willing to share my information to any laymen who needs assistance on resolving issues, choosing contractors, etc. But it's another thing entirely to think I'm supplying my intellectual property at no charge to someone who's using it elsewhere to make money. His inquiries lead me to believe he's doing projects and/or selling information to others. To me, that crosses the line of the intention of this website.

On the other hand, the pros on the site have their own side of the issues. They are highly educated (most) and speak the language. It's a known fact that because they're pros, they're in the trenches doing the work and/or representing manufacturers and/or distributors and have content to add to the mix. The level of expertise needed to answer most of the questions from DavidNJ are such that they are at pro level. Therefore, that's the forum where they should be, IMO. I only asked why he isn't so satisfy my curiosity as to why an inquirer would have over 900 posts if he's not a pro of some sort.

[DavidNJ]

I'd love to answer but I don't know what DavidNJ is all about. He'st got over 900 posts to this site, gleaning an awful lot of information, yet he refuses to become a pro member. I'm not bashing, I just don't understand. If a person is not in the trades, how is it he loiters around here daily, making all kinds of posts and doesn't qualify as a pro? So, no answer till I get an answer. Sorry.

I don't qualify as a pro member. If they want to wave the rule for being an HVAC pro...I fine with being a pro member.

Loiter is not quite the right word. An email notification comes when someone replies to a thread I was on; anyone I posed on I was subscribed to.

My threads occur when a new question comes up from research I'm doing for our new HVAC system. Buried in these threads is the explanation why that is taking nearly 3 months now. It took maybe two years before there was an HD camera I was comfortable enough with from a price/functionality standpoint (Canon 7D). This won't take that long, but could drag into the Spring of 2011 depending on equipment and contractor availability.

I came across this thread's topic just a few days ago looking at the different circulation pumps for a hot water heating system. Prior to that I had never heard of domestic hot water recirculation, which is probably evident by my first post in the thread.

[Mr Bill]

I don't have any problem with him, we did get off on the wrong foot with each other, he did not admire my humor, and I did not admire his narcissistic attitude. I just wondered how he has time for all his little projects as much time as he spends here. :D but for the record, IMO he's harmless, maybe lonely, needs some friends, just a guess, but like everyone, Mr. Bill loves him, well not in that way. :beat:

[commerce48]

It seems clear to me that he is completely focused on only his own home project and the issues involved. Just a typical engineer type that needs to analyze every variable. His research keeps bringing up new topics he want to explore in more depth. But even if not, it is not DIY so why not keep it public?

Some of it is way over my head, but some of his discussions have been the most useful of any I've seen here. I've been a little nutty myself reading this forum for the last year - I admit freely to loitering!. It would be a shame to relegate those discussions to the pro forums, even if he was allowed to do so.

[commerce48]

I don't have any problem with him, we did get off on the wrong foot with each other, he did not admire my humor, and I did not admire his narcissistic attitude. I just wondered how he has time for all his little projects as much time as he spends here. :D but for the record, IMO he's harmless, maybe lonely, needs some friends, just a guess, but like everyone, Mr. Bill loves him, well not in that way. :beat:

Narcissism? Where do you get that? This guy looks pretty focused on solutions. If you want to bring in motivations for posting in forums, well, everyone is basically going "look at me"!

[Mr Bill]

It seems clear to me that he is completely focused on only his own home project and the issues involved. Just a typical engineer type that needs to analyze every variable. His research keeps bringing up new topics he want to explore in more depth. But even if not, it is not DIY so why not keep it public?

Some of it is way over my head, but some of his discussions have been the most useful of any I've seen here. I've been a little nutty myself reading this forum for the last year - I admit freely to loitering!. It would be a shame to relegate those discussions to the pro forums, even if he was allowed to do so.

Very well said! I agree. http://i99.photobucket.com/albums/l286/mrbillpro/yes.gif

[Mr Bill]

Narcissism? Where do you get that?

Well you would have had to been around for our first showdown, and you would understand. Time to let it all go, time to move forward, who cares now, right? after all were in cyber space, probably lots of folks here we would all have a greater appreciation for, if we met them in person, except that Twilli dude, now he is just way out yonder, like Steve Winwood said, "can't find my way home". http://i99.photobucket.com/albums/l286/mrbillpro/Rofl_3g.gif

[USMC4LIFE]

When there is a demand for hot water at a faucet and the pump is operating, the valve under the sink closes. In fact once the water temp is 98 degrees the valve closes. This is what makes these systems operate like a thermostat controlled system

The comfort valve that Grundfos uses under the sink has check valves in it to prevent cold water from being pulled into the hot water lines while running hot water.

If you have muiltiple branches in the home you just add more valves under sinks and use the single pump. From what I understand a total of 7 comfort valves can be installed.

We had a client who stated they were tired of getting scolded from their failing grundfos comfort valves. He insisted we install the system he had ordered on the internet called a ready temp. It had a green Taco pump and a white box attached. The control box had temperature dial that you could set, a digital timer and a phone jack. The install was simple enough he could of done it himself. I think the real reason he called us was to remove the grundfos pump from the water heater along with the grundfos valve.

We were curious why the grundfos valve had been failing so using a vise we were able to slowly crack the valve open. The grundfos comfort valves utilize a tophat looking device inside made of thermoreactive rubbery polymer that suppose to soften when warm water contacts it. When softened by warm water it collapses the tophat shape allowing a check to close preventing hot water from going into the cold water side. Our best guess is calcium or other minerals built up in the valve preventing the check from closing.

Getting cold water is near impossible with these systems. Check valves in circulating pumps are there to stop cold water from mixing with the hot water, not the other way around. The ready temp we installed looked like nothing we'd ever seen before but did something different which made getting cold water not an issue.

I think most would agree its the cost of the energy put out by the water heater not from the pump that cost a heck of a lot more than the initial cost of these systems. Which when you think about it, connecting your hot and cold lines together with a valve that needs 98 degree water inorder to close means it's likely to be open more then closed. Now picture a home with 3 or 4 of these open valves throughout the home. And you want to try and get cold water? If you can't get cold water, there's only one place the heat is coming from, the water heater or more importantly your wallet. With the water heater being the 2nd biggest energy cost in the home, I be lookin to make it the most efficient possible instead of the cheapest you can get away with.