.3 gpm on hydronic heating -- help

josephny

I have an IBC boiler HC33-160 connected to a 4 loop EP manifold; each loop is about 250' of 1/2" hepex in joisttrak spaced 8" apart, with insulation beneath it and plywood subfloor and wood flooring above.

Pump is a UPS15-58.

Using water.

The house is poorly insulated.

I can't get the house to rise above 68* even with the radiant system running almost always.

I can feel the loops and they're nice and warm.

I put additional temp gauges on the copper in and out to the manifold, because I didn't trust the ep manifold's built in temp gauges. In is at 125, out is about 110.

Pump is set to high, but the flow rate, as indicated by the manifold's flow meters, never gets above .3 gpm. I have quadruple checked that the manifold flow valves are open all the way.

Is my problem the flow rate? If so, do I have an undersized pump or is something else going on?

Thank you!

kcopp

68F on radiant is pretty high. Is there a reason you want it higher? The boiler has an outdoor reset feature. It will change the water temp based on the outside temp. the boiler has some settings to change this feature. How big is this home? 160K is a large boiler for a home.

josephny

kcopp said:

68F on radiant is pretty high. Is there a reason you want it higher? The boiler has an outdoor reset feature. It will change the water temp based on the outside temp. the boiler has some settings to change this feature. How big is this home? 160K is a large boiler for a home.

68 is too chilly for us.

I'm not using the outdoor reset feature. Should I?

Small home -- ~1200 sq-ft.

How can I get the home warmer?

Is .3 gpm the issue?

Thanks!

Jamie Hall

Something does not compute. With your numbers I get around 2,000 BTUh. Unless my calculator has gone paws up...

I wonder what you are actually flowing?

Your delta T is quite reasonable, which indicates that your actual flow rates are also quite reasonable -- whatever they are. However, you can and should try running the floor warmer, if you want to be warmer -- although your input temperature of 125 is pushing it for radiant floors.

If your boiler has outdoor reset, and you are not using it, you should -- and you should see if it can be tweaked.

jad3675

I wonder how accurate the flow meters are?

Your boiler has a low fire rate of 30K - using this formula:
BTU = GPM * ((SWT-RWT) * 500.4)
You'd get 4GPM for a 30K BTU firing rate @ 15 deltaT. That seems a lot more reasonable that your .3GPM - that would about under 3K BTUs, which your boiler isn't capable of.

At full fire (140K), you'd need 18GPM to accomplish the same deltaT.

Math-wise, your pump should be more than capable of meeting the output of the boiler.

Robert_25

Those flow meters can be inaccurate. What is the surface temperature of your wood flooring?

hot_rod

heating 1200 sq feet with 1000' of tube? In a poorly insulated home! A load calc would be the first step, in some cases radiant alone doesn't meet the heat load. Then upgrade the structure as much as possible to lower the load.

neilc

poor insulation, you said it, my house also,
a few years back I found and sealed lots, LOTS, of air leaks,
never did add any insulation,
house feels much better, far less drafty.

I turned on both kitchen and bathroom fans on cold days,
(assuming fans vent to outdoors, and are not recirculating),
I went around feeling for, and caulking around window trims, floor baseboard trims, caulked or foamed baseboard to the floor, even pulled back carpet enough to caulk there also, etc,
made my air envelope at the sheetrock,
barefoot feet and toes make good draft detectors,

Can lights in ceilings? big holes, ceiling fixtures / ceiling fans? big holes,
with the fans on, hold the back of your hand an inch or 2 from an electrical outlet or wall switch,
wow, big draft from such a small device,
they make foam gaskets that go under the covers,
but I went insane and caulked or foamed all the holes inside the wall boxes, caution, live electricity,

all that said,
utility companies will, for a small fee show up, with a blower door and do some basic sealing for not too much $$,
call your fuel or electric supplier and ask,

josephny

I'm so sorry guys. I got very confused.

I'm using an SFC-199 combi boiler.

And the heated floor space is about 650 sq-ft (parts of the house extend past the basement, and I don't have access to install tubing under the floor).

And, the subfloor (the underside of which is where the joistrak's are attached) is old pine board. I believe there is plywood on top of that, and then common wood planking on top of that. So, probably about 2.25 to 2.5" of wood between the joisttraks and the room air.

Now that that's out of the way (very embarrassed)...

I raised the boiler temp to 140 this afternoon and I think it helped a little bit. Manifold input temp is 135; return is 115. So, I'm getting the 20* delta with 4 loops of ~250' each.

Does that mean that there's no way the flow meters are accurately reporting .3gpm each (1.2gpm total?)?

Plugging in to this formula:

BTU = GPM * ((SWT-RWT) * 500.4)
BTU = 12000

I think that if we assume these numbers are correct it would explain why I can't get the temp up higher: 12000 btu wouldn't be nearly enough to accomplish my goal.

Am I thinking about this correctly?

I can't upgrade the insulation of the house at this time.

Would it make sense to plumb in a flow meter on the input or return of the manifold so I can be sure of the flow rate?

Thanks!

psb75

I think you missed the point being made above. AIR SEAL first, then insulate when you can. Try to retain the heat you are desperately trying to supply to the space. That way, you will need to supply...less heat.

neilc

my point, shorter version,
air sealing is more important than insulation,
less invasive also

josephny

psb75 said:

I think you missed the point being made above. AIR SEAL first, then insulate when you can. Try to retain the heat you are desperately trying to supply to the space. That way, you will need to supply...less heat.

Thank you -- I do understand (generally) the importance of air sealing the space. I have looked at that and the only places I've found are the actual windows; that is around where the double hung sashes slide up an down the frame rails. Other than that, there are no identifiable leaks.

josephny

Is my concern about .3gpm for each of 4 circuits being too low misplaced?

KC_Jones

josephny said:

I think you missed the point being made above. AIR SEAL first, then insulate when you can. Try to retain the heat you are desperately trying to supply to the space. That way, you will need to supply...less heat.

Thank you -- I do understand (generally) the importance of air sealing the space. I have looked at that and the only places I've found are the actual windows; that is around where the double hung sashes slide up an down the frame rails. Other than that, there are no identifiable leaks.

Just to be clear, air sealing starts in the basement.  The chimney effect is what causes most of the issues.  The “space” is the entire house, even the unconditioned parts.

Go to the basement on a cold breezy/windy day, if you feel air, find where it’s coming in, be prepared with a can of spray foam.  I think you will be surprised how much you find.

What kind and how much insulation do you have under the radiant?

Jamie Hall

josephny said:

psb75 said:

I think you missed the point being made above. AIR SEAL first, then insulate when you can. Try to retain the heat you are desperately trying to supply to the space. That way, you will need to supply...less heat.

Thank you -- I do understand (generally) the importance of air sealing the space. I have looked at that and the only places I've found are the actual windows; that is around where the double hung sashes slide up an down the frame rails. Other than that, there are no identifiable leaks.

josephny said:

Is my concern about .3gpm for each of 4 circuits being too low misplaced?

Some work on those sashes should get them to the point that when the window is closed and locked there is very little draught -- if any. That said, the work is a bit painstaking, and there aren't all that many carpenters out there who can -- or will -- do it. Also, if you have to replace bits (particularly the parting rails), which you may, it's really important to use air dried, well seasoned wood, and cut and shape it to fit properly.

On the 0.3 gpm being a concern -- it would be, if it were real. But there's no way it can be that low and still provide the heat.

hot_rod

Two ways to increase output, increase flow or raise SWT. Are you sure the manifold ports are wide open?

josephny

I have worked for hours, reading instructions and watching videos and examining the flow control adjusters. I even turned one too far counterclockwise and discovered they do indeed unscrew entirely and come apart. So, yes, I am certain the adjusters are wide open.

I thought maybe there was an obstruction in the loop, but not all 4 loops.

I ordered 2 Uponor TruFlow meters (one .15-.8gpm and the other .25-2gpm) that (I hope and believe) will be as simple to install as just disconnecting the loop at the manifold and putting the meter inline.

At lease then we'll have another flow rate reading.

But, could all 4 of my current flow meters be that inaccurate?

Just in case I've completely lost my mind, here's what I'm looking at:

neilc

FWIW,
i see you closer to .4 gmp than .3,
and 1/2 gpm should be close enough,
remind again, what's that water temp ?
surface type and temp ?

Zman

I am thinking there is another issue with your circulation. Either some incorrect piping or some resistance you have not considered.

Can you post pictures?
Are you piped primary/secondary like the manual shows?
Have you pulled and inspected the circ?
Are you sure the circ is set to high and that the lever is connected to the mechanism inside?
Are you able to check the amp draw of the circ?

This is what your flow and BTU rates should be (on paper)

Zman

It sure would be easier to help you if you would stop creating new posts.
Looking at the pictures from this post, is that a strainer or check valve on the return side?
https://us.v-cdn.net/5021738/uploads/editor/3o/d2ddn5ts38as.jpeg

josephny

Got it -- thank you.

1) I am piped primary/secodary
2) That is a strainer on the return side on the secondary.
3) The circulator was initially installed (not by me) in reverse. I then reversed it to make it flow in the correct position and have since learned and implemented the correction (with help from the forum) that the motor part of the pump (I think it is) can be removed with 3 hex head bolts so that the black plastic wiring and speed control is on top. (Also replaced the wire with a oil/water resistant jacketed wire more neatly tied to the plywood; and connected the consensate neutralizer, etc.)
4) I have not checked the pump nor do I even know about a level -- I don't know how to do that.
5) When I am next onsite I will check the current draw on the pump.
6) I can confirm that the pump is warm (even hot) to the touch.
7) Should I be shooting for 1.28gpm per loop?

Now I'm pondering the idea that somehow the pump is pumping in the wrong direction. Would I get .3-.4gpm/loop if that were the case?

neilc

other than the manifold,
have you, could you post a picture of the boiler, et al

josephny

I've been researching air separators as a result of the idea that maybe the pump is air-locked.

I came across this video that shows Caleffi has an antisuction cap for the air separator for times when "you're going to have a possible suction on your air vent," as the engineer in the video states.

My air separator in just inches before the pump -- could this be the problem?

https://youtube.com/watch?v=xG2ySwPS6kM

Zman

You might check that strainer. I chunk of teflon tape could cause all of this.

josephny

neilc said:

other than the manifold,
have you, could you post a picture of the boiler, et al

https://us.v-cdn.net/5021738/uploads/editor/3o/d2ddn5ts38as.jpeg

josephny

Zman said:

You might check that strainer. I chunk of teflon tape would cause all of this.

Certainly worth taking a look -- will do, thanks.

Zman

As long as you have positive pressure in the system, the vent should not be an issue.
Have you tried power purging the loops one at a time using the fill valve and the manifold purge points?
Have you verified that the manifold parts are assembled correctly? Stranger things have happened, even from the factory.
I am not sure you will get 1.28 GPM, I would expect at least 1 GPM with that setup.

jpulls11

Zman said:

You might check that strainer. I chunk of teflon tape could cause all of this.

I’m curious about that too. Because that strainer comes with the boiler and is supposed to be installed on the cold water inlet for the one demand portion of the domestic water.

josephny

Zman said:

As long as you have positive pressure in the system, the vent should not be an issue.
Have you tried power purging the loops one at a time using the fill valve and the manifold purge points?
Have you verified that the manifold parts are assembled correctly? Stranger things have happened, even from the factory.
I am not sure you will get 1.28 GPM, I would expect at least 1 GPM with that setup.

My understanding from Caleffi's video is that the suction created by the pump might cause the air circulator to suck air into the system. Is that not correct? Is there no problem locating an air separator several inches before the pump?

I haven't tried power purging the loops, but I will.

I wouldn't know if the manifold is assembled correctly or not.

Seems like 1gpm would be a huge improvement (I'll take it!).

josephny

jpulls11 said:

Zman said:

You might check that strainer. I chunk of teflon tape could cause all of this.

I’m curious about that too. Because that strainer comes with the boiler and is supposed to be installed on the cold water inlet for the one demand portion of the domestic water.

I don't believe this strainer comes with the boiler and, while I understand that pex minimizes the need for such, the strainer is there to protect the more delicate parts of the system, such as the heat exchanger. As such, seems to make sense to put it where it is.

jpulls11

josephny said:

You might check that strainer. I chunk of teflon tape could cause all of this.

I’m curious about that too. Because that strainer comes with the boiler and is supposed to be installed on the cold water inlet for the one demand portion of the domestic water.

I don't believe this strainer comes with the boiler and, while I understand that pex minimizes the need for such, the strainer is there to protect the more delicate parts of the system, such as the heat exchanger. As such, seems to make sense to put it where it is.

I’ll have to find it in the manual. However, each one has come with a 1/2” or 3/4” strainer depending on the size of the boiler. 

Zman

Even though your vent is on the suction side of a small circulator, it is also located with the expansion tank (point of no pressure change). That circ will not pull air as long as the expansion tank is charged and system pressure is maintained.

If your strainer has a very fine screen, you might try running without the screen installed and see what happens.

josephny

Zman said:

Xmas said:

Even though your vent is on the suction side of a small circulator, it is also located with the expansion tank (point of no pressure change). That circ will not pull air as long as the expansion tank is charged and system pressure is maintained. If your strainer has a very fine screen, you might try running without the screen installed and see what happens.

There is an automatic feeder but other than that (if that at all) I haven’t pressurized the system.  Do I need to check the pressure?

Jamie Hall

josephny said:

Zman said:

Xmas said:

Even though your vent is on the suction side of a small circulator, it is also located with the expansion tank (point of no pressure change). That circ will not pull air as long as the expansion tank is charged and system pressure is maintained.

If your strainer has a very fine screen, you might try running without the screen installed and see what happens.

There is an automatic feeder but other than that (if that at all) I haven’t pressurized the system.  Do I need to check the pressure?

Wait wait! Say what? What pressure is your system running at now? Hot and cold?

josephny

Jamie Hall said:

josephny said:

Zman said:

Xmas said:

Even though your vent is on the suction side of a small circulator, it is also located with the expansion tank (point of no pressure change). That circ will not pull air as long as the expansion tank is charged and system pressure is maintained.

If your strainer has a very fine screen, you might try running without the screen installed and see what happens.

There is an automatic feeder but other than that (if that at all) I haven’t pressurized the system.  Do I need to check the pressure?

Wait wait! Say what? What pressure is your system running at now? Hot and cold?

I have just about no knowledge of this aspect of the system.

The DHW cold side comes in from the pressure tank which will be between 40 and 60psi.

The space heating side has an autofiller which I have not adjusted (i.e., I have no changed the setting of).

I filled the heating side (primary, secondary, loops) by straightening the autofiller's top level. I have no idea of the pressure. I thought that over time the autofiller will maintain the pressure and the air separator would remove the air.

How wrong am I?

psb75

You aren't wrong. Sounds like you have filled the system--maybe even overfilled it with the "fast fill" lever.
You could make up a simple device of a pressure gauge with a hose fitting and put it on the boiler drain valve and then open the valve and check the actual system pressure.

josephny

psb75 said:

You aren't wrong. Sounds like you have filled the system--maybe even overfilled it with the "fast fill" lever.
You could make up a simple device of a pressure gauge with a hose fitting and put it on the boiler drain valve and then open the valve and check the actual system pressure.

I just ordered the pieces to do this. I couldn't find a pressure gauge with garden hose thread that had a scale with a top of lower than 100psi, so I got one with a 1/4" npt 0-60psi and a 1/4" npt to garden hose adapter.

Is overfilling the same as over-pressurizing?

So, if the air separator is in a good location in the system and removing air, and the system is not under-pressurized, that leaves a clogged filter or malfunctioning pump as possible reasons for the low flow rate, right?

(I'm not onsite so I can't check the filter or pressure today.)

Thanks!

hot_rod

you are sure the circulator is pumping into the top manifold? should be an arrow on the cast iron pump body.
My next thought would be the Y strainer, just remove the mesh and see what happens.

Paul Pollets

If your wood floor thickness is beyond 2-21/2" thick, you're beyond the recommended thickness advised by manufacturers, which is usually 11/4"max. High resistance usually means floor conditioning is possible, but maintaining a 68 degree setpoint may not be. A heat loss calc using radiant software would tell you. It presumes you have R19 min. under the plates within the joist bays. Adding supplemental heat may be advisable, and you certainly have enough boiler size. Do the math using the actual defaults for floor insulation and thickness and you'll know.

josephny

hot_rod said:

you are sure the circulator is pumping into the top manifold? should be an arrow on the cast iron pump body.
My next thought would be the Y strainer, just remove the mesh and see what happens.

First on my list of things to check when I'm next at the location.

Will definitely report back.

Thanks!

josephny

Paul Pollets said:

If your wood floor thickness is beyond 2-21/2" thick, you're beyond the recommended thickness advised by manufacturers, which is usually 11/4"max. High resistance usually means floor conditioning is possible, but maintaining a 68 degree setpoint may not be. A heat loss calc using radiant software would tell you. It presumes you have R19 min. under the plates within the joist bays. Adding supplemental heat may be advisable, and you certainly have enough boiler size. Do the math using the actual defaults for floor insulation and thickness and you'll know.

I will double check, but I'm pretty sure that above the tracks are pine boards (either .75" or 1"), then plywood (.75"), then wood plank flooring (.75"), for a total of 2.25" to 2.5" of wood.

I'm pretty sure I have 3.5" mineral wool under the tracks, which I'm pretty sure is R15 (could be R19).

I was wondering about adding supplemental heat using the same system by adding something like this:

https://supplyhouse.com/Buderus-3-41236-Model-21-12-x-36-Hydronic-Panel-Radiator

But (like everything) I've never done it and know nothing about them. Best I can do is an assumption that it will be a second zone?

Thanks!