Radiant Heat Loop Not Working #2

Jolly Bodger

I suggest it it the flow-check. Have you opened it up to see if the circuit flows?

Remember, head is cumulative. Every little thing adds up. Once it gets over the curve of the pump. Flow stops.

HomerJSmith

Are you telling me that one pex circuit is 24' long and one pex circuit is 18' long, that is supply and return to the manifolds? That would be slightly unbalanced, but no need to worry. Yes or no.

HomerJSmith

Jolly Bodger--Pressure loss or head loss is cumulative, but I know what you mean.
To be a successful plumber, one only need to know 2 things--Payday is on Friday and water FLOWs downhill. The emphasis is on FLOW.

Jolly Bodger

You know, Head of resistance.

DZoro

Dear @ John Siegenthaler, this is one for your fix .
Their maybe some disappointed faces when the fix is done....
I'm sure you can pump away at it.
May have to use your imagination at the actual piping diagram.
Just a thought, no rush there is time.
Dennis

Ralphxyz

Remember the Radiant Loop heats when the house circulator is running so there is not anything restricting the flow except possible the Flow Check Valve.

OPERATING INSTRUCTIONS
Flo-Control Valves are vertical lift check valves that function
when the system pump starts . Flo-Control Valves are
designed with a handle that when turned fully counterclockwise will permit gravity circulation. This is useful in emergency
situations whenever electrical power is lost and only partial
heating is possible.
During system filling and purging it may be helpful to Manually
open the Flo-Control Valve to aid in air removal. Do, this by
turning the handle counterclockwise to the fully open position.

I turned the Handle counterclockwise two turns, the stem comes out and leaks. It made no difference, still no heat! How far should I turn the handle? Will it stop or come apart?

Ralph

HomerJSmith

Ralph, I haven't seen any action from you. There have been plenty of recommendation from the professionals here. Why you haven't even done what Jolly Bodger recommended with the Flo-check. It take 2 sec. and gives important information. Getting a drawing or pic from you is like pulling teeth.
I feel like I'm playing a game of "Yes, but". I don't feel like playing anymore. My time is precious. I'm 2 days older than Moses. I don't have much left, but I would like to spend it helping people, not playing games.
This blog is already 3 pages long.

Jolly Bodger

The Flow-check test may not fix it. It is simply something to try. Manual and my recollection is turn it counter clockwise until it stops. Yes it will leak. It has probably never been moved. Tighten the packing nut.

@DZoro I would love to see this solution you are alluding to. I'm all about learning and soling puzzles. I find it harder when I can't get my hands on it. Can you share, John did not get tagged.

rick in Alaska

Ok. I am game to give it a try.
I would put a bypass line from the hot supply going in to the mixing valve, and tie it in to the return line below. Install a globe valve or circuit setter in this line. Then, on the supply line going out to the rest of the house, after the tee that splits for the mixing valve, add a zone valve.
Wire it up so the house thermostat powers up the zone valve, and then the zone valve end switch goes to the tt on the boiler. Then get a single zone pump control like a Taco or Caleffi, and wire up the radiant thermostat to it. Use this control to turn on the radiant pump, and take the tt contacts off this control back to the tt contacts on the boiler. So, what happens is if you want house heat, the zone valve opens up and turns on the boiler and circulator. If the house heat is not on, and the radiant comes on, the thermostat for the radiant will turn on the radiant pump control, and the tt contact on the control will turn on the boiler and the boiler circulator. If both systems are on, then both pumps will still be operating, but now the zone valve will be open also.
But, you will need to close down the globe valve/circuit setter to get the flow going to the house piping, but have enough left over to get back to the boiler return. Most likely you will find that the globe valve/circuit setter will be mostly open.
My money says this will work for you. At least it has on a few jobs I have done.
Rick

DZoro

hot_rod said:

https://www.pmmag.com/articles/84495-a-little-floor-warming-please-john-siegenthaler

Do it right the first time, imo.

You have a simple 2 zone system. Problem is that it is not designed correctly. Just because you "think" the water "should" do this and that. Doesn't mean the water is listening to you. That tee that your trying to draw maybe some hot water from is just that a tee, and water can come from 2 directions. Water doesn't understand human thoughts it has to be forced to do what we want.
2 zone systems need correct designing or failures will occur.

Mixing valves don't know what to do when it sees water of the same temperature. We have to help them with the water temperature difference and then it will know what to do.

All the work you did putting up all those pressure gauges confirm all of this. When the mixing valve sees nothing but cold, it cannot open itself up. When it sees hot and cold it understands and proportionally opens itself up for flow.
D

Jolly Bodger

@DZoro No doubt this is not how most of us would have piped this from the start and re-piping it correctly would make it work.

Do mechanical thermostatic mixing valve "see" incoming temperature? This is not my experience. If that were the case it wouldn't matter what port you put the hot and cold to. I believe it just sees it is below setting so shift to the hot port or sees it is above setting so shift to the cold port.

hot_rod

DZoro said:

Dear @ John Siegenthaler, this is one for your fix .
Their maybe some disappointed faces when the fix is done....
I'm sure you can pump away at it.
May have to use your imagination at the actual piping diagram.
Just a thought, no rush there is time.
Dennis

I already showed Siggy's fix, the 3 piping options a few posts up "A Little Floor Warming Please"
Sept 2001 Plumbing and Mechanical magazine

https://www.pmmag.com/articles/84495-a-little-floor-warming-please-john-siegenthaler


People have been trying to make 3 way mix valves do things they weren't designed to do for generations

HomerJSmith

Gee! A Taco i-Series 3-way set point mixing valve would solve all Ralph's problems as long as the radiant pump as enough head energy to overcome the sys pressure loss (head loss). You might still have to regulate the flow to less than 2 g/m and you might have to install a spring check valve at the output of the boiler pump.
DZoro, says, "That tee that your trying to draw maybe some hot water from is just that a tee, and water can come from 2 directions." Close but no cigar.
Can we all agree that flow occurs when and only occurs when there is a pressure differential. Isn't that what a pump does, creates a pressure differential. Flow moves from high pressure to low pressure. It works with the weather, too. That flow of air is called wind. It works with dams to create electricity. I think a lawyer would call that "settled law". Can we, also, agree that flow follows the path of least resistance (also "settled law"). A closed gate valve has infinite resistance to flow.
Imagine this, there is no RTI valve. It is just a straight piece of pipe. With the radiant pump running what would the circuit be back to the input of the radiant pump?
Wouldn't it be--the output of the radiant pump to the supply manifold, thru the pex to the return manifold, thru the boiler, air scoop, and flo-check, to the tee, back to the input of the radiant pump. As long as the radiant pump can output sufficient head energy to overcome the pressure loss (head loss) of the circuit flow would occur. Can we agree on that?
But, is there an alternate path that water could go as DZoro says or Groundup implies? Yes, possibly, and that would be a reverse flow thru the boiler pump, thru the heat emitters, back down the supply pipe to the tee, to the input of the radiant pump. Groundup would run a supply pipe from the RTI to the air scoop which would put the supply to the RTI before the flo-check. The flo-check would eliminate any reverse flow thru the boiler pump to the RTI and the new supply pipe would reduce the pressure loss (head loss) of the radiant circuit. In terms of pump selection any reduction of pressure loss (head loss) in a circuit is a good thing.
But, is it necessary? One would have to know the resistance of the heating circuit and one would have to know the resistance of the radiant circuit to know what reverse flow is occurring. Flow is going thru the path of least resistance.
Suppose we put infinite resistance in the boiler circuit, like a spring check valve on the output of the boiler pump. Would that prevent reverse flow? Would that eliminate DZoro's second flow from the heat emitters thru the tee to the RTI?
Considering the above, with the radiant pump off and the boiler pump on, how does one prevent reverse flow thru the radiant circuit. The boiler pump is going to push water in the direction of least resistance. Either thru the heating circuit or the radiant circuit or both. Put infinite resistance on the radiant circuit, maybe like a swing check between the boiler pump and the radiant circuit?
Of course, if it is decided that a higher head radiant pump is needed, one can leave the check valve in the radiant pump's volute and not use a swing check.
To be truthful, I don't know if a Thermostatic Proportional, 1017, mixing valve need equal pressure on both the hot and cold input or whether the valve need to see hot water before it will allow flow as DZoro says. My unknowing thought is that a flow occurs thru the valve regardless of whether it sees hot water, just not a mixed flow or maybe the valve shuts down.
My course of action: 1). Do what Jolly Bodger says, open the flo-check and with the radiant pump on and the boiler pump off, then see if you have flow thru the RTI. If yes, get a bigger pump. 2). If no, put a spring check on the boiler pump output and repeat #1. If yes, close the flo-check. Do you get flow thru the RTI? If yes, then the radiant pump can handle the pressure loss (head loss) of the circuit, but at what flow, remember you want between .5 to 1.5 g/m thru the pex. If no, you need a bigger pump. I would leave the spring check valve in the volute of the new pump.

HomerJSmith

All you great and wonderful people out there, spending your day with family and friends, I wish you all a very, very happy Thanksgiving.
We have much to be thankful for.

HomerJSmith

Look, I have no objection to Groundup's idea of running a supply pipe from the RTI to the air scoop before the flo-check. It would eliminate reverse flow and lower the pressure loss (head loss) in the radiant circuit. One could eliminate the spring check on the output of the boiler pump. But, there may be other concerns as to whether one gets flow to the RTI.

HomerJSmith

DZoro says, "I'm all about learning and sol[v]ing puzzles." DZoro you are a man after my own heart. As long as I can take a breath, I want to learn.
I also know that knowledge without application is sin and knowledge without sharing is sin.

Jolly Bodger

@HomerJSmith too often we see application without knowledge!

HomerJSmith

Jolly Bolger--Yup, but life has a way of correcting that.

Ralphxyz

WITH the FLOW CHECK open the Radiant Loop HEATS as it should!

My service man was at the house fixing a new/different problem and he suggested I replace both circulators with circulators with built-in check valves (IFC) leaving the Flow Check open.

The House circulator is a Taco 007-FA, which of course is discontinued.

I am open to suggestions!

Ralphxyz

That is the radiant loop heats without the house circulator running with the flow check open!

HomerJSmith

Walla! That was a long time in coming. Replace both pumps with a Grundfos 15-58 with the flow check in place in the volute. Set the boiler pump to speed 1 (low) and that would be the same as the 007 in terms of head energy. Set the radiant pump to speed 3 (high).
I wouldn't change anything else in term of piping changes until that is done.
Realize Ralph, that the flow thru the radiant circuit is unregulated, but the flow rate may be between .5 and 2 g/m with just the 15-58 on speed 3.
The only way to be sure of the flow thru the radiant circuit is with a balancing valve set to a flow of 1 g/m or what ever, but I would be inclined to not do that and just adjust the speed of the pump and observe the result.
https://www.supplyhouse.com/Grundfos-59896341-UPS15-58FC-3-Speed-Circulator-Pump-1-25-HP-115-volt-4701000-p
Happy Thanksgiving!

hot_rod

Judging from this drawing you have two loops around 200' or so long? 1/2 gpm per loop or 1 gpm total. Mix valve, some piping and fittings, I'd guess that 15-42 would be plenty of pump?

Unless that is 1/4" tubing

GroundUp

Jeepers dude, what part of the 15-42 curve are you having trouble reading? There is NO PROBLEM WITH THE CIRC. So with the flow check eliminated and money spent on unnecessary pump swaps with IFC, what's going to stop ghost flow through the radiation when only the radiant is calling? Parallel flow is going to occur on the supply side out of necessity to reach the tee, and continue up to the radiation. That IFC in the boiler circ will do nothing

Jolly Bodger

Now that we know where the restriction is, all you need to do is leave the flow-check open and put a spring check after the house circulator. This would be the same as installing a pump with a check valve. I don't think you need a check in the radiant loop. It is unlikely that you would get unwanted flow through it.

HomerJSmith

Said earlier.----"Look, I have no objection to Groundup's idea of running a supply pipe from the RTI to the air scoop before the flo-check. It would eliminate reverse flow and lower the pressure loss (head loss) in the radiant circuit. One could eliminate the spring check on the output of the boiler pump. But, there may be other concerns as to whether one gets flow..." and what that flow would be.
If you want IFC's You are going to have to replace the pumps. If you want to keep the flo-check, you need to do what Groundup recommends or replace the radiant pump with a higher head pump. It was not determined that the 15-42 was capable of providing enough head energy to create flow in the radiant circuit without the boiler pump until Ralph did what Jolly Bodger recommended, opening the flo-check and seeing if the 15-42 could create flow other than doing a complete pressure loss evaluation of the radiant circuit and looking at pump performance curve.
A 15-58 is a cheap pump cost wise and fits right into the space of the 15-42. A lot less work than re-piping as Groundup suggest and gives you 5' more of head energy which is exactly what Ralph's pressure gauges showed what the boiler pump added in terms of flow.
I can read a pump performance curve just fine. I can see that at a flow rate at 1g/m, the pump puts out 14.25'hd. About the end of the pump curve for the 15-42.
Groundup, before you do your "happy dance" realize your suggestion was a lucky guess that happened to be right. It could have just as well have not worked considering the 15-42 pump performance curve.
Ralph could just remove the flo-check and the 15-42 would work, but other problems could occur such as ghost flows. But, the flo-check information wasn't known until the flo-check was opened.
Ralph has options as to how he wants to solve his problem. He can choose.

Ralphxyz

It is 1/2" tubing, the 20' between the circulator and mixing valve and radiant loop is 3/4" soft copper so no fittings in line.

Using a spring check or even two would save some money and appears to be a solution. Adding new circulators w/check valves does not really add anything.

The radiant loop circulator works with the Flow Check open so why not just add some check valves?

What might I be missing?

Ralph

Jolly Bodger

@Ralphxyz , Nothing. Put a check in on the discharge of the house circulator. Open the flow-check and see how it runs.

HomerJSmith

Jolly Bodger--Cheap and effective.

HomerJSmith

The boiler water is always at 160F. Opening or removing the flo-check would allow thermo siphoning on the supply piping. Just something to think about. A problem who knows. More of a problem if it is a mult-story building.
Groundup's recommendation would stop thermo siphoning up to the baseboard, but allow thermo siphoning up to the RTI but that may be a good thing.

Ralphxyz

Would there be thermo siphoning if there was a spring check on the house return?

Could I take the radiant loop supply off the back of the flow check? Currently there is a plug in the back of the flow check.

I am "thinking" of putting a spring check on the house return below the circulator, though I do not see where position matters
the check valve is active when the circulator is not on, and opening the Flow Check. Just to see how that works.

Ralph

HomerJSmith

Ralph, I can see you don't want to do too much work--that's good.
Work is the devil's playground.
Yes, I don't see why not. The bottom port should pass tru to the plugged port.
Since you aren't coming off the tee and the tee will be capped and you are keeping the flo-check, I would forget the spring check on the output of the boiler pump. Gee! It's getting simpler and simpler.
Of course, if it were me, me being a very difficult person, I would still install the Grundfos 15-58 with the Internal Flow Check on the radiant circuit. I got a whole shelf full of them that I got for peanuts. Well, not literally for peanuts. So it is easy for me to do. It is your choice and you can always do it later if need be.

Ralphxyz

Actually I have already done a lot of work on this, I repiped the circulator location three times.

Essentially even though there is a union the 1 1/4" supply pipe is a dead hitch and it would not be "easy" to put a tee in at the air scoop so if I could just take the radiant loop supply off the back of the flow check that would be easy.


I really liked the 3 speed and the internal check valves of the Grundfos 15-58.

Moving the supply tee will not hurt and might be all that is needed so I "think" I will do that. If that does not work I will put a spring check (which I have coming) on the house return.

Thanks again and again for all of the help!!

Ralph

HomerJSmith

Ralph, as I stated, you are pumping into the expansion tank. You would be well advised to move your Xtank to the input to the boiler pump. About 10" from the input. Keep your air scoop where it is.

Ralphxyz

Thanks HomerJSmith, that is interesting, input to the boiler pump
being on the return?

The expansion tank has been where it is for 15 years what would be the advantage of moving it.

When I was a kid expansion tanks were always under the air scope.

Ralph

HomerJSmith

Errors can be practiced for a long, long time. Watch this Caleffi video. It will tell you why you should move it. Start at 7min 9sec. Figure 7-1a is your system setup. Notice the big x across it?
https://www.youtube.com/watch?v=6kbT1_2Xjn4

Ralphxyz

Thanks if I need to install the spring check on the house return I'll need to take the return piping apart so I could "easily" move the expansion tank.

HomerJSmith

Like I said I probably wouldn't put a spring check on the boiler pump for the following reasons:
1) The spring check is going to use up the boiler pumps head energy to open it.
2) When the radiant pump is running and the boiler pump is off the chance of reverse flow thru the boiler pump is nil as the flo-check won't allow reverse flow.
3) With the radiant and boiler pumps running there wouldn't be any reverse flow, the flow thru the boiler would just increase.
The only reason that I can see for a spring check is to prevent thermo-syphoning thru the boiler pump. That should be the coldest point in the sys. The flo-check is right where it should be to prevent thermo-syphoning on the supply piping (hottest water).
If there is any where that I would put a check valve (swing check) it would be, before, where the radiant circuit plugs into the output tee of the boiler pump to prevent reverse flow thru the radiant circuit when the boiler pump, only, is operating. This is why I said, if replacing the 15-42 pump with the 15-58 pump leave the volute IFC check valve in the volute and forget the swing check.

hot_rod

I would add the check in the circ, they add very little pressure drop, see attached.

Really only 1 application where i would use a swing check in a hydronic system, on a wood fired boiler where you want flow in a power outrage

Swing checks are not" bubble free" basically meaning the do not seal tightly.

And they need a ∆P to even close at all. In a hydronic system when the circ is not running, the pressure on inlet and outlet will be the same, there is no pressure against the gate to close and seal it.

Swing checks are great for sump, sewer and other pumps that have pressure available to shut and seal the flapper.

Weighted flo-checks, like you have or low pop spring checks for hydronics.

Jolly Bodger

@Ralphxyz let us know how piping the mixing valve supply into the back of the flow-check works. It looks good on paper. Would like to see if it is the simple solution in reality.

I agree with @HomerJSmith , if this works there should be no need to check the boiler pump. That was the "open flow-check install spring check" solution.

HomerJSmith

"Hot Rod" I watched part two "Coffee With Caleffi" in 2016 and I watched twice again 2 days ago. Thanks for a great job. You amaze me. I've learned so much from you and Caleffi makes great products.
"Swing checks are great for sump, sewer and other pumps...", indeed they are as long as they are mounted horizontally. And they do leak, my real concern in this application would be chattering.
I would prefer a new 15-58 with an IFC, but I believe his drawing of his radiant sys would allow the boiler pump to induce flow to the cold port of the RTI, even with the IFC in the 15-58, when the radiant pump isn't running and the boiler pump is. Would the cold port allow water past the hot port and therefore complete a reverse circuit thru the boiler? It would depend on the delta P. But any flow even if it is very low would steal head energy from the boiler pump
The swing check before the tee on the output of the boiler pump would solve any reverse flow thru the radiant circuit and the RTI cold port and he can keep the 15-42 radiant pump if he makes the other required piping changes.