Zone Valves to stop Ghost Flow

Shadowdoc

Attached is my heating system layout. Boiler is a Teledyne JVT100NDI (133,000).

3 Circulating pumps (CP).

CP3 is for bypass to maintain return temp, BUT when CP3 runs, it draws heat through the entire system, even when a floor has no call for heat.

2 story older home. About 1800 sq ft split evenly between 2 stories. Mostly PEX piped. There about 200 linear feet of PEX running along the unheated basement ceiling for supply and return.

MY QUESTION: Can I just ADD 2 Zone valves , 1 above each zone circulator pump, which are on the return side to control flow and stop ghost flow caused by CP3?

STEVEusaPA

I would try flow checks first.

Shadowdoc

There are 2 flow check valves on the supply side. There isn't any back flow. CP3 draws from the entire system when it runs.

pecmsg

What is the pipe size coming out of the boiler 1 1/4" that loop should stay that size then reduce to the zones.

Ironman

Move the bypass circ to here:



Or use closely spaced Tees to create a proper p/s loop.

NY_Rob

What's with that pressure relief valve (bottom photo)... it looks like it would just shoot hot water out horizontally across the room?

Shadowdoc

As you can see from the second picture there’s really not enough space to put the bypass circulator pump in that location.

Ironman

Shadowdoc said:

As you can see from the second picture there’s really not enough space to put the bypass circulator pump in that location.

Make room. Turn the Tees 90* and extend the loop as much as needed.

Shadowdoc

Thank you. Makes sense.

Big Ed_4

I agree with ironman , I would perfer repiping it primary secondary with the proper spaced tees ... Easier and cheaper to pipe it right ..

Shadowdoc

I plan on moving the CP3 by extending the bypass line.

But I am curious. By “repiping”, would that mean repiping the primary loop with larger diameter pipe, like 1 1/4” and then use closely spaced tees for each of the 2 secondary loops (zones) and leaving all that piping the same, 3/4”?

Sorry but I am a curious type. Thanks in advance.

hot_rod

What temperature are you suppling to the floor?

Shadowdoc

It’s set at 190*

Ironman

hot rod said:

What temperature are you suppling to the floor?

I think he was referring to a first and second floor level, not a radiant floor.

Shadowdoc

68 to 70°… There is no radiant floor. I apologize for my lack of knowledge here.

I was thinking what the gas boiler temperature was set at.

hot_rod

Are you sure about that boiler spec, a JVT 100 should be a 100,000 input, around 80,000 output?

Unless the bypass pump is on a control sensing return temperature it really doesn't do much "protecting'

a three way thermostatic boiler return valve would be a better option, or a tekmar control to operate the bypass pump.

With a low mass, low volume boiler and if you have copper fin tube baseboard, a return protection piping may not be needed?

Laars shows piping it with a bypass piping with zone pumps, in the installation manual.. You might just pipe it without bypass pump and a valve to balance some bypass. That would solve the ghost flow as long as the pumps have checks at the discharge.

Primary secondary or a hydraulic separator would be the ideal piping.

Shadowdoc

I was just poking around the boiler and noticed there are 2 flow check valves on the supply side and they are set differently.

One is turned down going to the down stairs and the other up (open) going upstairs.

The ghosting only occurs when there is a call for heat downstairs. This causes heat also upstairs.

When the heat is called for upstairs, there is no ghosting downstairs.

Any thoughts?

hot_rod

to work properly a flow check, they need to be screwed down, clockwise.

The way it is currently piped, those checks may not be adequate to overcome all the pump delta P. You have pumps in series, doubling the head. To correct properly, get out then tubing cutter I'd add a better air removal device also. I'm not sure how deep you want to get into upgrades?

How old is the boiler? has it been serviced regularly? Any sign of flame roll out near the burner?
Those copper fin HX need to be cleaned and checked, especially if you suspect cold operating conditions.

A CO detector would be a nice addition to the boiler room.

cubbydog

I believe this is the future of hydronic heating!

hot_rod

I would avoid any device, or piping that reduces flow on the suction side of a circulator, or causes turbulent flow conditions both the flow check and Y strainer in that drawing.

A brand new 1" y strainer has pressure drop, which only goes up as it does its job.

A circulator with internal check is the best protection, it was built specifically for preventing ghost flow.

Actually a hydraulic sep would do a much better job of the 4 functions you need, dirt, air, hydraulic and magnetic separation.

And it can locate the expansion tank in a better spot.

Cleans up the piping connections also.

cubbydog

Agreed, but the concept of injecting boiler water with the return water is going the result in longer boiler life. Delta T

hot_rod

cubbydog said:

Agreed, but the concept of injecting boiler water with the return water is going the result in longer boiler life. Delta T

I believe that is a copper fin tube boiler, the pumped bypass if more for protecting against low return temperature.

HomerJSmith

I have used Taco I-Series set point sensor mixing valves for by-pass on Lochinvar mini fin boilers set to 135 deg. Worked great to protect against low boiler return temps. Most boilers condense on start-up and this helps minimize that because it is close between the input and output of the boiler.