Baseboard Heat - gravity problem?

asperber

I have a 5zone hydronic baseboard system in my house but have a problem in some of the rooms. Even with the thermostat off, I still feel the baseboards get warm. The contractor put in 5 Taco 007-F5 Pumps. If I am reading correctly online, those do NOT have a check valve internally? If that's the case, is my problem that there is a gravity problem feeding hot water to my upper floors unintentionally?

Any help would be greatly appreciated!

STEVEusaPA

I think you figured it out. Internal flow checks would be easiest and hopefully work. Re-piping with flow checks and/or heat traps would be better.
Why 5 zones? This will introduce other problems, most likely short cycling (unless this is a properly sized mod-con that can turn down far enough).

asperber

STEVEusaPA said:

I think you figured it out. Internal flow checks would be easiest and hopefully work. Re-piping with flow checks and/or heat traps would be better.
Why 5 zones? This will introduce other problems, most likely short cycling (unless this is a properly sized mod-con that can turn down far enough).

Thanks for the quick response. Can I convert my taco pumps and put in internal flow checks? Or would I need to swap them out?

I like having 5 zones, but the problem is that the brilliant contractor put in 5 circulator pumps. Our house isn't big enough to justify that. We could do with 1 pump and 5 zone valves....

asperber

...

Jamie Hall

You can leave the Tacos and put in external flow checks.

asperber

Jamie Hall said:

You can leave the Tacos and put in external flow checks.

Thank you @Jamie Hall . Something like this?

https://www.supplyhouse.com/Taco-220-6-1-Universal-CI-Taco-Flo-Chek-1991000-p

hot_rod

Check with Taco, possibly you could slip a check right into the pump body. That would be the easiest correction.

Here is another add-on option, with sweat/ union connection.

asperber

Thank you @hot rod. Potentially dumb question, but I am a homeowner learning about this. Do you need a flow check on both sides? Or just the return side?

hot_rod

Just one side, typically 6-8" downstream of the circulator.

When were the five 007s installed? Most all circulators come with check valves either installed or packaged in the box.

asperber

Here are two pictures of my setup. Where would I put the check valve? If my circulator pump doesnt have one internally, wouldn't i need one on both sides of the circuit?

hot_rod

A few things going on, I think. Looks like the pumps are on the return pumping into the boiler?

Also looks like they are pumping towards the expansion tank location, not ideal.

I'd suggest a few changes pumps on the supply side of the boiler with checks added.

Hot water, like hot air rises, it is possible to get some ghost flow, hotter water rising up those vertical lines while cooler water falls down, a thermo-siphon of sorts.

In that application you want checks on the supply lines.

A repipe could correct the pumping away from the expansion tank(s) and solve the ghost flow.

You already have the pumps, I suspect 1 pump and zone valves could better do the work required. Five 70W circulators doing the work that 1 could, possibly.

Are both expansion tanks connected together? iwonder why two?

asperber

I am trying to avoid an entire repipe, at least until I replace the boiler. I actually put in the air separator in the back with the expansion tank. I was informed that it's good practice to put the extra tank in, although not necessary.

So if I put 5 flow checks on the supply side of the line, that should help eliminate the ghost flow? Do I need it on the return side as well? Or that side shouldn't heat up the water as much?

Thanks again.

HomerJSmith

There is nothing wrong with zoning with circulators. If your taco pump volute is chambered for a check valve, you can ask your installer for them as they come with it. If your volute isn't chambered, the check valves won't fit into it and you will have to use an inline check valve. What's happening I think is when a pump turns on it pushes a little bit of flow thru the other pumps in a reverse flow.

hot_rod

I doubt that installing checks in or at the circulators will help, the circs need to be on the supply to have that work effectively.

Also the header that all the branches connect to needs to be sized for the combined flow when all circs are running, hard to see if that is the case in your piping. That piping becomes sort of a low loss header.

I don't know what the loads are on each zone, or total load, I suspect with 3/4 tube maybe 3- 4 gpm max? I wonder if any of those circs are running efficiently? 350W to move how much load? On low load days those circs may be all the heat input needed

One circ can typically move 100- 120K. Possibly with 37W with current ECM technology. Why 5- 70W circs?

I think I would wait until all the piping corrections can be made or upgrade to a single ECM and ZVs if distribution efficiency is part of the objective.

A complete analysis of the system requirements would be the best first step before a remake. Combining zones could maybe help with cycling with that type of fixed speed boiler.

My suggestion would be:
Room by room load
Properly sized boiler
Select emitters to work with lowest temperatures
ECM circulator to get the best electrical efficiency

asperber

I agree that what we have is WAY overkill and unnecessary. I'm not looking to take on a huge project such as redoing the entire system, with 1 circulator and 5 ZVs right now. But if I read that correct, putting the check on the return wouldn't do anything.

In my situation, would putting it on the supply still help?? At least mitigate the problem until we replumb the system.

It won't help the fact that I'm drawing 3.5 amps when they are all running however

Zman

I agree that the system should be repiped.
I also get that you would like to find a less costly option.
I suspect most of the ghosting you are getting is due to reverse flow through off zones.
I suspect snapping these into the circs will solve the immediate problem. https://www.supplyhouse.com/Taco-006-047RP-IFC-Replacement-Kit-for-Select-Taco-00-Series-Cartridge-Circulators?gclid=EAIaIQobChMI1Y_AsIKi2QIVlYdpCh2nQAbTEAQYAiABEgIKXfD_BwE

asperber

Would that help as much as putting checks on the supply side?

Zman

It will get rid of the reverse flow that I suspect to be you problem.
If I was going to spend the time to put checks on the supply, I would just move the circs.
Your install has multiple issues: circs on the wrong side undersized header, overpumping ect. It sounds like you just want to fix the ghost flow, internal checks will do that.

asperber

Zman said:

It will get rid of the reverse flow that I suspect to be you problem.
If I was going to spend the time to put checks on the supply, I would just move the circs.
Your install has multiple issues: circs on the wrong side undersized header, overpumping ect. It sounds like you just want to fix the ghost flow, internal checks will do that.

Would those work with the 007-F5 (NON IFC) pumps? Is that a retrofit?

Zman

@Dave H from Taco could probably tell you when the changed the casting to accept the IFC. My guess is that they would fit.

EBEBRATT-Ed

How many zones do you get the unwanted heat in. Just 1 or all 5?

If it is only one or two zones just put flow check(s) or a zone valve on the offending zone. If your going to repipe and use zone valves when you do just put a zone valve on the offending zone and have the end switch on that zone valve start it's respective pump

george_42

I have been a plumber for over 50 years , and every packaged boiler we ever put in had circulations on the return side . I realize that today the feeling is to pump away but millions of boilers were installed pumping on the supply and they work perfectly.

Zman

@george
There is nothing wrong with circs on the return side as long as you put the expansion tank there.

I think pumping incorrectly showed less symptoms when systems were simple baseboard loops and cast iron boilers with relatively small circulators. Today's radiant systems and water tube boilers with high head circs do not function when piped incorrectly.

NY_Rob

If you don't want to do any soldering, you can just add a flange type check valve between the pump and existing flange. Since you have Pex after the near boiler piping.. just cut off a length equivalent to the height of the flange check valve and it's gasket. No soldering!

https://www.supplyhouse.com/Webstone-13703HV-3-4-to-1-1-4-Isolator-Double-Flange-Check-Valve

hot_rod

You may still get some ghost flow if you leave the circulators where they are and add checks into or after them.

It is possible under some conditions to get two directional flow, especially with vertical piping like those supply.

It is more common with larger diameter piping that allows two direction flow, but it happens in pex piping like that also. I have seen it in fin tube baseboard. It is a slow, gradual overheat symptom.

If you are going to jump into it why not correct it with either circulators on the supply, or possibly a single circ and zone valves on supply.

An ECM with zone valves would bring that into the current, state of the art distribution piping.

Big Ed_4

I have been a plumber for over 50 years , and every packaged boiler we ever put in had circulations on the return side . I realize that today the feeling is to pump away but millions of boilers were installed pumping on the supply and they work perfectly.

Pumping away from the tank helps greatly with the old air bound problem ... Pumping away from the tank increases the pressure in the heating loop which decreases the size of air bubbles . Pumping toward the tank the **** end of the circulator would be the heating loop , the pressure decreases making the air bubbles increase in size ... Easier to move small bubbles in an water flow then killing the flow with an air pocket .. Check out "pumping away "for extra info of air removal ...

Yes they still install an package boiler with the circulator on the return ... Easier to crate and stack ..

Yes we use to install circulators on the return but we also install flow valves on each zone to solve the over heating problems .

hot_rod

Back with the old B&G style circulators pumping into the boiler and towards the exp tank was not such a big deal. Those old 1725 rpm flat curve circulators only developed around 6' head at 10- 12 GPM.
The higher rpm, steeper curve wet rotors are when the pumping towards became more of a problem. With a high head circ it's possible to pull sub atmospheric conditions.