Mystery flow in new secondary loop - and it's backwards!

Quercus

I finished my primary-secondary repipe just in time for our dip into the 20's Saturday night. I am very pleased with the operation of the main circuit but the baseboard loop is puzzling me.

I had some sort of flow that had the bedroom addition overnight at 68 while the thermostat was at 64. I used to get mystery flow in that circuit which I attributed to the two pumps being next to each other on the return line. I have a flow still and I noticed this morning that the return side of this circuit is hot while the supply side is cold (circ is off, T-stat set to 55). This is during a heat call on the main circuit.

For reference, the first tap off the primary is the bedroom baseboard with the green 007. The main house is the bumblebee circuit. Also, the before photo is included that is not truly before, but shortly after breaking into things.

Should I be getting induced flow on this layout? Are the circuits too close?

Thanks,
Steve

STEVEusaPA

Yes, and yes. You are too close together between branches, probably too close to the elbow. Maybe some flow checks on supply/return could prevents some repiping.

hot_rod

You should have check protection on the S&R for all the p/s takeoffs. This is especially important when you have vertical take-offs.
Do the circs have checks inside them? if so install some hydronc spring checks on the returns.

While not ideal, the spacing between take-offs it should work properly.

Are all the heat emitters low mass baseboard? i don't see any return temperature protection if you have any mass connected to that non-con.

Tinman

Non-con. I like it.

Quercus

There is a flow check in the bumble bee with nothing on the baseboard circuit. 007 green is feeding baseboard in a master BR and the yellow pump is the rest of the house, which is CI converted gravity system.

The elbow is preceeding the 007 that pumps away. Steve, are you saying that distance is critical?

Any recommendations of swing vs. spring checks? How do I do checks on S&R? They have to be in the same direction, don't they?

I was trying to perform the temp protection by using setpoint control on the system pump. Originally I was planning to use a thermostatic valve in system bypass but felt this approach gave me greater flexibility. Original system had NO control or protection whatsoever and I don't feel I am much better at startup.

I can get a check valve in that circuit easy enough but will tough it out another winter before cutting into the primary loop. The boiler is 23 years going with no protection at all.

Here is a look at what I had just before the point of no return.


Thanks for your help
Steve