12 year old radiant system had circulator switched from supply side of manifold to return

Ben Greenfield

It's a long story and I was startled by the overall result of the "upgrade" but as a radiant enthusiast I Would like professional opinons regarding the move of the circulator from the supply side to return. The radiant system and low-temp baseboard are secondary loops from the main loop.

This was working but I was told I needed to add a circulator on the main loop. I had this done and they redid the layout of everything moved the circulators to return side just before the main loop.

The radiant system is now exhibiting problems getting heat to each run on 1 manifold. I tune the individual zones to get the zone working which usual works temporarily. Either another zone or the same zone will become cold in a day or 2.

I don't recall ever needing to adjust the the zone vales before the "upgrade" in fact I never understood the use of those valves until I tried to get those cold zones balanced.

Thanks for your input.

Ben

icesailor

Can you post any photo's of the "upgrade" and any of how it was done before?

Harvey Ramer

Rule#1 If everything works properly, safely, and efficiently; just let it be!

More then likely, since they moved the circs over to the return, they are pulling air in through an auto air vent somewhere. It could also be that the circs are not hydraulically isolated.

Also import, is the pressures at each port on the mixing valve for the radiant. The circ should be placed on the mix port pumping away from the valve and into the radiant loops.

Please take some photos that clearly depict the current piping layout. We can help get this figured out.

Ben Greenfield

Harvey Ramer said:

Rule#1 If everything works properly, safely, and efficiently; just let it be!

My old main loop wasn't as good as the main loop they put in. The rest of it is highly suspect to me.

More then likely, since they moved the circs over to the return, they are pulling air in through an auto air vent somewhere. It could also be that the circs are not hydraulically isolated.

That could be as I pointed it out to them they told me it was probably air. They was about a month ago.

Also import, is the pressures at each port on the mixing valve for the radiant. The circ should be placed on the mix port pumping away from the valve and into the radiant loops.

That was what I had. If I understand correctly.

Please take some photos that clearly depict the current piping layout. We can help get this figured out.

Great thank you.

Ben

Ben Greenfield

before pictures sorry not so good I will look for better. The picture with the map shows the main loop with the supply coming from another building. The 2 orange zone valves are for the secondary loop. The main loop is that little rectangle

Harvey Ramer

Harvey Ramer said:

Also import, is the pressures at each port on the mixing valve for the radiant. The circ should be placed on the mix port pumping away from the valve and into the radiant loops.

This is the problem. The water is short circuiting through the mixing valve and back through the pipe to the inlet of the circ. It will be quite impossible to make it function properly with this configuration. Those 2 circs for the radiant need to be moved to the supply side, pumping away from the mixing valve and into the radiant manifold.

Harvey

Harvey Ramer

Another thing. Not sure what kind of manifolds you have there, but the front bottom is usually the supply. You'll want to make sure that you are pumping into the supply manifold so your flow meters will function properly. "typical manifold" Check manual.

Harvey

Ben Greenfield

Harvey Ramer said:

Harvey Ramer said:

Also import, is the pressures at each port on the mixing valve for the radiant. The circ should be placed on the mix port pumping away from the valve and into the radiant loops.

This is the problem. The water is short circuiting through the mixing valve and back through the pipe to the inlet of the circ. It will be quite impossible to make it function properly with this configuration. Those 2 circs for the radiant need to be moved to the supply side, pumping away from the mixing valve and into the radiant manifold.

Harvey

When I first saw this asked about the circulator move and they told me that all the younger guys were now installing this way.
I was already so skeptical at that point I didn't bother engaging and just wanted them to finish and leave.

Are you really sure everything hasn't changed since Dan wrote pumping way the guide book I used 12 years ago:)

Harvey Ramer

Pumping away is pumping away from the point of no pressure change "exp tank"

Ben Greenfield

Harvey Ramer said:

Pumping away is pumping away from the point of no pressure change "exp tank"

So the direction is only in relation to the expansion tank, there could be circumstances that a return side circulator makes sense.

The other secodary loop is a hot water baseboard and the return side placement doesn't seem to hurt it.

Ironman

One other thing to note beside the problem with the circ location which Harvey pointed out: you're piped p/s series. This means that each descending secondary loop receives the cooler return water from the previous loop. This may not be a problem if the descending loops are receiving hot enough water from the primary. At the very least, it may reduce efficiency if the boiler has to run at a higher supply temp to compensate.
Piping it in p/s parallel would have eliminated this issue.

Also, is this an in-slab system? If so, you need a smart valve or variable speed injection mixing based upon outdoor reset to control it properly. A dumb valve (TMV) is not the proper component.

icesailor

Just because "all the young guys are doing it like this" is his reason, doesn't mean that "All the Young Guys" are correct. Nor may he be.

Just because some of us are old, doesn't mean that old theories and practices are wrong or have been replaced.

With my "old fashioned" understanding of Primary/Secondary piping, that always worked for me, I wonder how many "Young Guys" that are doing it like this have successful systems, or are really just HVAC people, unlicensed and untrained to be doing hydronic/radiant piping. A way to connect their Air Handlers, Duct Board and Flex Duct systems to a hot water boiler.

I can not for the life of me understand what their intent was. Other than practice using their new Pro-Press machine and fittings. Somewhere in my misunderstanding of P/S piping, I was under the mistaken impression that the closely spaced tees on a secondary loop connected to a primary loop were to be "closely spaced". Like something like 4 to 6 pipe diameters apart. And that there should be an obvious farther spacing between any other secondary circuit connections. So as not to create excessive turbulence in the primary circuit. By the circuits being too close together.

Those "Young Guys" must be smart. I'm not.

Ben Greenfield

Ironman said:

One other thing to note beside the problem with the circ location which Harvey pointed out: you're piped p/s series. This means that each descending secondary loop receives the cooler return water from the previous loop. This may not be a problem if the descending loops are receiving hot enough water from the primary. At the very least, it may reduce efficiency if the boiler has to run at a higher supply temp to compensate.
Piping it in p/s parallel would have eliminated this issue.

I will look up what piping in p/s parallel is. I have already redrawn the layout to not be so ridiculous but I will look at this parallel business to see if I think I need it.

I think I made that design decision eyes wide open. The radiant system is in a large 12" bed of sand that acts a heat storage and radiant heat. This is the first secondary loop the second loop is low temp baseboard in another building. The baseboard covers the entire perimeter and operates at very low temperatures. The radiant system really dictates temperature needed.

To tell you the truth it has been 10 years since I even looked at boiler temperature. Once I get this thing back in order I will start to see how low I can go.

Thanks for the help this board is the best.

Ben

icesailor

@Harvey Ramer:

"" More then likely, since they moved the circs over to the return, they are pulling air in through an auto air vent somewhere. It could also be that the circs are not hydraulically isolated. ""

More than likely, they are NOT. Auto float vents do NOT suck air when on the "suction/return" side of a circulator if there is sufficient system pressure. Unless you have a way oversized or overdesigned system that is creating excessive velocities or pressures. It just doesn't happen. If you have an oversized pump in a heating system that is creating suctions well below negative zero, you will hear the cavitation. It sounds like ball bearings inside the pump.

Go play with some shallow well pumps and wells where the screen is plugged and the vacuum is up to a 25' lift.

If you close all the caps on a heating system with float vents and still get air, where is it coming from?

Cavitation. Which occurs from excessive velocities or excessive turbulence.

In my experience and opinion.

icesailor

Another thing.

You said that the source is in another building. What size is the main supply to the disaster?

I'm may be wrong (and usually am), but that primary circuit is only 3/4". It is way too small. It should have been a minimum of 1" or 1 1/4". There is a serious pumping issue there. It might have been marginal under the best of conditions. The "followers of "All the young guys doing it this way" are clearly on the wrong path to understanding.

Ben Greenfield

Ironman said:

Also, is this an in-slab system? If so, you need a smart valve or variable speed injection mixing based upon outdoor reset to control it properly. A dumb valve (TMV) is not the proper component.

This is my own fault. I treat my heating system more like a model railroad set. I'm constantly trying different controllers and what not and went way out of my way to buy those crazy dc variable valves.

I'm certainly not your run of the mill heating customer but I don't hold any of the contractors responsible for any of my hare-brained schemes on heating. I do expect a certain amount of pride and workmanship for the work they perform.

Ironman

Ben Greenfield said:

Ironman said:

One other thing to note beside the problem with the circ location which Harvey pointed out: you're piped p/s series. This means that each descending secondary loop receives the cooler return water from the previous loop. This may not be a problem if the descending loops are receiving hot enough water from the primary. At the very least, it may reduce efficiency if the boiler has to run at a higher supply temp to compensate.
Piping it in p/s parallel would have eliminated this issue.

I will look up what piping in p/s parallel is. I have already redrawn the layout to not be so ridiculous but I will look at this parallel business to see if I think I need it.

Thanks for the help this board is the best.

Ben

The attachment that I posted shows the most common method of p/s parallel piping: aka the moose antler.

If the base boards are designed for a lower temp than what is coming from the return on the floor, you're OK. But if not, then it needs to be piped p/s parallel.

Ben Greenfield

icesailor said:

Another thing.

You said that the source is in another building. What size is the main supply to the disaster?

I'm may be wrong (and usually am), but that primary circuit is only 3/4". It is way too small. It should have been a minimum of 1" or 1 1/4". There is a serious pumping issue there. It might have been marginal under the best of conditions. The "followers of "All the young guys doing it this way" are clearly on the wrong path to understanding.

I have 1" supply and return and everything else is 1" excepting the low-temp baseboard is 3/4".

If you are truly curious my entire history of posts on the wall are regarding this system which includes lively discussions about feas/sense/ability of what I'm tinkering with here.

Prior to the upgrade of the main loop everything worked in that regard. After the upgrade I notice the baseboard circulator is using 25 watts at times with 0 gpm on an grundfos alpha. The other day for the first time ever I heard a weird vibration sort of sound on the this same circulator but it cleared up.

Are those symptoms or just things that happen?

Thanks,

Ben

icesailor

@Ben Greenfield:

Last night, I watched 60 minutes on TV. They did a piece on Mandy Patinken. He has had a hobby of model trains since he was a child. He has a huge set up in his cellar, with all types and gauges mixed in. There is a big trap door in the middle so you can watch. A camera was in the whole looking back where there was a big Lionel AC transformer and controller. There was a tribe of 3 track Lionel AC track. Much of the trains though were HO Gauge that run on DC. There has to be some AC/DC rectifiers somewhere and DC controllers.

Knowing your trains and the voltages they require is like knowing how your heating system works. If you have too many trains on the tracks, you might need bigger controllers.

Ben Greenfield

icesailor said:

@Ben Greenfield:
Knowing your trains and the voltages they require is like knowing how your heating system works. If you have too many trains on the tracks, you might need bigger controllers.

The final piece of the set for me is when I replace the house's steam heat with some sort of radiant/low temp baseboard.

I'm considering trying to install a Daikin Altherma as a hot water source.

I don't know why more people don't take an active role in their heating I find it fun.

Zman

The comments above concerning "pumping away" are right on.
The other problem I see is that the circ is not located within the heating loop.
With this setup, every time the radiant loop gets too hot, the flow to the loop will be restricted. Bad plan.
Carl

Harvey Ramer

@‌Icesailor

I am perfectly aware of what you are saying Ice, and you are correct. It doesn't normally happen. Nonetheless, I have seen it happen and it can be caused by more than one thing.

And you never know what someone has done to a system when they show up here with a problem.

Harvey

Ben Greenfield

Harvey Ramer said:

Another thing. Not sure what kind of manifolds you have there, but the front bottom is usually the supply. You'll want to make sure that you are pumping into the supply manifold so your flow meters will function properly. "typical manifold" Check manual.

Harvey

I forget the manufacturer of the manifold but it came pre-assembled with topmeter valves in this orientation. I used to have the circulator on supply side with check valves now the circulator is on the return side with no check valves anywhere.

I want to make sure I understand your opinion is that the circulator should be on the supply side to insure the flow meters function. I just double checked and the supply side is definitely the top back manifold.

Harvey Ramer

"I want to make sure I understand your opinion is that the circulator should be on the supply side to insure the flow meters function. I just double checked and the supply side is definitely the top back manifold."

My only concern is that you are sending the water through the manifolds in the proper direction in order to make the flow indicators work.

The circ being on the supply is required by your mixing setup.

Just to clarify, it is not a rule that a circ has to be on the supply in every situation. For example, if you were doing injection mixing, the radiant circ could just as readily be on the return.

Harvey

SWEI

Ben Greenfield said:

I'm constantly trying different controllers and what not and went way out of my way to buy those crazy dc variable valves.

Those look like Belimo CCV's. How did you size them and how are they controlled?

Ben Greenfield

They are Belimo TR24-SR. I'm currently using a Canakit relay board that connects to the Belimo's with a diode and a computer through USB although the computer see it's as a terminal device.
I currently have a computer acting as the controller with stupid software I wrote. I'm getting ready to move to something based on this.

http://openenergymonitor.org/emon/emonBase/NanodeRF