Recirculation hot water systems

We recently moved into a 7 year old single story home. It is quite long from one end to the other with bedrooms at both ends. The primary water heater is in the center of the home in a closet. There is a small water heater in the crawl space that appears to serve only one bath/bedroom on one end directly above it. The remainder of the house (kitchen, laundry, powder room, bath/bedroom at the other end) all seem to take hot water from the primary tank. The reason I say that is the one bedroom gets instant hot water and the rest of the house you have to wait up to a minute or so to get hot water.

I followed the piping from the small water heater in the crawl space and very near to it is a mixing valve with the outlet that appears to feed the toilet to prevent sweating.

My question is this: Is that mixing valve supposed to serve as a cross connection to allow instant hot water throughout the house as well?

Pictures help. what you may think is a mixing valve maybe something else.

just a guess, but is there a hot water line from the main tank going toward the smaller heater. might be they use the small heater for quick hot water and maybe feed that with hot from the main tank. Not normal as described but been in the biz for along time and seen a lot of "not normal" configurations.

Mr_David said:

Pictures help. what you may think is a mixing valve maybe something else.

just a guess, but is there a hot water line from the main tank going toward the smaller heater. might be they use the small heater for quick hot water and maybe feed that with hot from the main tank. Not normal as described but been in the biz for along time and seen a lot of "not normal" configurations.

Click to expand...

pictures please...

http://http://i436.photobucket.com/albums/qq81/donl1150/Domestic%20Water_zpshjrz1fls.jpeg

Well, I believe I have drawn up my complete domestic water system. It is easily accessible in the crawl space and I have done my best to draw it up with a program I found on line. We have our own deep well system that is supplied by a constant pressure pump.

The dark blue lines are the cold water lines; the red lines are the hot water lines and the light blue lines are mixed hot/cold that supply the water for the toilets to avoid sweating during the humid times. You will see the house is quite long (110') with BR's at each end. The two mixing valves are shown along with a photo of the mixing valve.

My goal is to reduce the time needed to get hot water to the remote areas with the minimum amount of work/cost. Since there is no actual 'return' line to the water heaters, I am wondering if it would be possible to perhaps replace the mixing valves with just a tee and then install a circ pump at the far end? Does it make any difference that we are on a constant pressure well system vs a city supply?

After thinking and reading more about these systems, wouldn't I be best served by installing a recirc pump that takes its suction supply from the 3/4" hot water line leading OUT OF the small water heater and then pipe the discharge into the 3/4" hot water line at the opposite end of the building near the bedroom? That would create a hot water loop using the 50 gal tank as the source. I assume I should put a check valve on the discharge side of the pump...or do they have checks built into them?

why do you have both heaters tied into together? my suggestion.

cut them loose. then see if your problem still exists

donl1150 said:

We recently moved into a 7 year old single story home. It is quite long from one end to the other with bedrooms at both ends. The primary water heater is in the center of the home in a closet. There is a small water heater in the crawl space that appears to serve only one bath/bedroom on one end directly above it. The remainder of the house (kitchen, laundry, powder room, bath/bedroom at the other end) all seem to take hot water from the primary tank. The reason I say that is the one bedroom gets instant hot water and the rest of the house you have to wait up to a minute or so to get hot water.

I followed the piping from the small water heater in the crawl space and very near to it is a mixing valve with the outlet that appears to feed the toilet to prevent sweating.

My question is this: Is that mixing valve supposed to serve as a cross connection to allow instant hot water throughout the house as well?

Click to expand...

to answer your question. no, the m/v does not service the house

if your drawing is correct, it mixes water for the toilet