Replies

1. 
   G.LaLonde | Feb 22, 2000 10:37pm | #1

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   Is there a pump on the system??

2. 
   Guest_ | Feb 23, 2000 03:11am | #2

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   Mitch, I don't have the FHB issue you mentioned but I'll throw my two cents in FWIW.

   As I understand the hot water loop system it relies on the convective current generated as the warmer, less dense liquid rises in the line and the cooler, denser liquid ahead of it falls (gravity) via the return loop to the tank. There are no mechanical forces acting on this flow.

   This motion can only be sustained if there is always a temperature differential throughout the line and no point of stoppage such as a high point where an air bubble can form or a mechanical stoppage such as a stuck check valve.

   1. Check the check valve.

   2. Check for an air bubble trap

   3. Did you insulate past the high point of the system? If the water is warm on the way back down for any length (how long I don't know) it will be less dense and fight the return force of gravity, which is the other end of the convective loop, effectively slowing or stopping the flow.

   Comments? Ralph

1. 
   Guest_ | Feb 23, 2000 04:50am | #3

   *I've never seen a return loop system in a residence but have had them in every hotel, medical center, and school I ever worked in. They always had a circulating pump.

3. 
   Mitch_ | Feb 24, 2000 12:29am | #4

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   Thanks for your input. Opened the valve, It seems to be working OK.
   The return is at the most distant point from the heater. The return is 1/2" and "T"s into the shower riser at the higest point possible.
   The return is level for some distance(folowing the joists) and then slopes down to the heater. No "U"s in the system. I did insulate the return but pulled that off. Should the return be 1/2"? Should the return be "T" into a riser or be "T" at the feed line? When the system was working, the return was warm to the touch at the heater and all of the feed lines were warmer to hot. Frustrating thing was that I thought I would need a pump. But the system worked for a little while without one.

1. 
   Mitch_ | Feb 24, 2000 12:38am | #5

   *No pump. When I did this, my understanding was that the system would to work on a one story residence without a pump. And it does (did) but then it quit again. I am trying to figure out what I did to make it work and why it quit. I suspect that something in the system design is marginal.

4. 
   Mitch_ | Feb 24, 2000 12:38am | #6

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   My house has a hot water return loop, see Fine Homebuilding 1992 vintage, to maintain a constant flow of warm/hot water in order to provide quick hot water at the tap. First problem is that it never worked. However after I plumbed a lower bath the system magically started working. The wife was happy, life was good. Concerned about heat loss through the lines, yesterday I started to insulate. Now, this morning the system magically stopped working. What is going on? How do I restart the flow? The system has a check valve at the bottom of the tank but no valve at the top. Can anyone help with advice on how to make this thing work?