hot water recirc pump

[gfe76]

I have a bell & gossett NBF-22 (.8 amp. 92W) pump. House is old 5 bath with new "L" grade copper pipes. Just insulated them with 1" wall foam. Seems the water heater cycles on more with the pump than when it was just gravity fed.
1. Will this pump cause me to use more gas to run the water heater?
2. If I turn the pump off will it still circulate with gravity or will the pump prevent a gravity recirculation?
3. Can I put a bypass around the pump and only use the pump at nite right before the kids take baths, then turn it off and just open the bypass?
Thanks

[jadnashua]

Many of the recirculating pumps run on either a timer or a manual momentary switch that causes the pump to run until it senses the water is hot, then shuts off. I don't think that you need a bypass, I think the water will go around the pump vanes regardless (but I don't know that for sure!). You will probably get some convection flow unless you put a check valve in the system (unless there is one built into the pump). By running the recirculating pump, you will use more gas - the pipe acts as a radiator (slowed if you have them insulated) - so, by keeping the pipes hot, you have to replace the heat lost to the house by running the hw heater.

Note, I'm not a pro...

[gfe76]

thanks jim....I hope a "pro" out there can give me an answer...that is why I gave the model #. I don't know if the pump has a check valve...there is one in the pipe line just before the recirc water enters the tank. Not sure if the "vanes" of the pump will allow gravity to recirculate. A timer won't work because the way our family is hot water is needed on the second floors almost anytime of the day...thanks again

[hj]

The circulation line will cause the heater to operate more frequently and use more fuel because you are constantly reheating the water in the pipes as it cools down. It will also shorten the heater's life due to this added operation. You must have a check valve between the pump and the heater or you will have erratic water temperatures. Whether the system will operate on convection depends more on how the pipes are arranged, (and unless it was designed for a convection system it will probably not work anyway), and the check valve will minimize the efficiency when the pump is off. DO NOT install a bypass unless you want to disrupt the entire hot water system's operation. A temperature controlled switch sounds like a good idea in principle, but since it is controlled by the temperature of the water at the heater, it can allow the water at the far end to become cold before restarting.

[gfe76]

thanks hj.....it was originally a convection setup....when I re-piped the plumber suggested the pump...the orig system had a check valve and it is still installed...I think I'm sorry I put the pump in. that is why I was going to do a bypass and only use the pump on occasions. I certainly don't want to shorten the life of the heater or add to my already high gas bills. I'm leaning toward a timer and just time it so it comes on for a few hours in the moring and a few hours at nite.....thanks so much...

[hj]

Any convection system, whether with a pump or not, if it is working properly, will add to the fuel bill and shorten the tank's life. It is a function of keeping the water hot, not pumping it. One "fix" is to install a "globe" valve between the pump and the tank and then close it until just enough water circulates to keep the system hot. This will also minimize any erosion from excessive velocity. Do not put the valve before the pump and do this however or you will damage the pump.

[gfe76]

thanks hj.....great idea...by "globe" do you mean "ball" valve? when I replumbed all I installed were ball valves...i think gate valves are trouble waiting to happen....One last curious question...always wondered if you have a ball valve only slightly open will the flow of water "wear" the edges of the ball so that it will eventually not seal with the teflon/plastic seal when closed? thanks

[Mikey]

I'm just finishing up replumbing my house overhead after discovering many small leaks in the under-slab copper pipe. The overhead route is a little more circuitous than the under-slab plumbing was (presumably), so I'm looking for a hot-water recirculation system that will operate on demand. I imagined what I would like, and Viola! found what appears to be exactly it -- the Chilepepper system (http://www.chilipepperapp.com/Default.htm). They've apparently been around for a while, and post glowing testimonials (what other kind?) on their Website. Does anyone have any experience/opinion about this?

[hj]

thanks hj.....great idea...by "globe" do you mean "ball" valve? when I replumbed all I installed were ball valves...i think gate valves are trouble waiting to happen....One last curious question...always wondered if you have a ball valve only slightly open will the flow of water "wear" the edges of the ball so that it will eventually not seal with the teflon/plastic seal when closed? thanks

NO. While a "globe" valve might make you think of a ball valve, the description actually applies to the fact that the valve body itself is sort of globular. It is actually a compression valve with a washer, not much different than a tub or sink valve. Its advantage is that it can be "throttled" down to a minimum flow without wearing the mechanism out.

[rickford66]

I have one of these gravity recirc systems, and I don't care about the increased cost. I love it!! After all, how much could it be when you factor in that when the heat is lost, it is heating the house, reducing the load on the furnace. 100% of the lost heat goes into the house, which isn't so bad in the winter. Yeah, it might not be as efficient as the furnace, but at least there is some offset. When I come in from working on a car, or something similar, I love the fact that I can wash my hands with warm water and the water heater is at the opposite end of the house. I'll never give it up... NEVER!!! You can't make me. :O) I wouldn't want the type that uses the cold line for the return, because then, you might end up waiting for cold water instead. Anyway, that said, I'm using a ball valve to restrict water flow from the bottom of the tank. I read here that there might be an issue with the valve wearing out? Is that really a problem with such a mild flow?
Thanks.

[hj]

IT will not "wear out", but it is more difficult to adjust if you are trying to use it to regulate the flow.

[rickford66]

Not really trying to regulate flow with any real accuracy. Just trying to reduce the amount of water coming from the bottom of the tank when hot water is turned on in the house. It's been 3 years so far and it still works great. Thanks.