Problems with Radiant Floor System

smuth10

Just found this forum and I was hoping someone could help me with my radiant floor setup. I will try to keep it as short as possible, but here are the basics.

This system was put together based off of many others with similar setups on the garagejournal.com forum.
Shop is 30x40 with finished attic space
4 loops 250-300ft each
2" rigid foam underneath slab with 1\2" O2 barrier pex stapled to that
4" slab
R19 in the walls. R30 in the ceiling
30% Glycol
Grundfos UPS15-58FC, 3-Speed
HWH is a Takagi condensing that is rated for in floor heating. T-H3M-IN-NG
Installed by me. Licensed contractor. Not a mechanical contractor


I know I will be immediately bashed for using a hwh and that is fine. I know a boiler is a much better option, but I did not have the extra money at the time or I would have.

The system started up fine and seemed to be working great and then the hwh started to vibrate badly. Manufacture said it was the glycol boiling and that I needed to increase the pressure. I did this and it did help a little, but the problem was still there. The other forum guys said the filter was dirty and I should clean it. I cleaned the filter and it did seem to help quite a bit. Was getting 2 gpm and the temp was set at 120, no vibrations. Kept cleaning the filter and it is completely clean now when I take it out. Vibration came back after running for 15-20 minutes and the only thing that has worked was turning down the temp to 110 on the hwh. Guys on the other forum said the most likely culprit was air in the system. Sounded reasonable to me so I flushed the system for 15-20 minutes with my Wayne pump and charged it to 15 psi. I was working in the shop all day yesterday and the system did not even come on until later in the afternoon. Went out there to check it last night and the call for heat was on and the pump was running, but the hwh was not on. Restarted everything and it came back up, but I noticed the gpm slowly going down until it went to .4 gpm and then the hwh shuts off. Tried to re-cycle several times and same result.

The part I don't understand is that there are numerous people out there with an identical setup and they work just fine. That, and it worked fine for 2 days before taking a dump.

Any help would be greatly appreciated and I will gladly pay a pro in my area to come by and go over my system. I am in the SE Michigan area if anyone has a referral.

GW

I'm sorry I dont have much experience with water heater installs. How about isolating the wh from the system, hook a hose up to the cold, run another hose outside, and see what happens? You need to know if it's a wh problem or a system problem.

Your positive each loop is purged?

did you leave the flow check in the pump?

I don't recognize that manifold, are those actuators/ zone valve heads?

Is that a high efficiency unit? You have plastic venting but no condensate drain?

Gary

smuth10

As far as I know each loop is purged, but this is the first time setting one of these up so not sure how to tell.

No, I took it out

They help you adjust the flow for each loop. They are all the way open right now

That is the venting it calls for and I did not have the condensate in at the time of the pic. It is in now and the unit makes a lot of condensate. A lot

Gordy

Agree where is the condensate going there is a condensate drain on that unit?

Sounds like a flow issue. Did you purge each loop individually wide open?

smuth10

It is in the back left corner. I have it going to to about 6" from the floor.

I opened them one at a time when I was pumping the solution into the system. Should I have been doing something different? How would I do it now to ensure they are purged?

Gordy

How strong is the pump your using for purging? Need good flow.

Right procedure. Are you flowing into a bucket until no air bubbles are visible.

smuth10

Yes, I am. I am using a Wayne PC4 pump.

smuth10

So I decided to close off the last 3 loops and try to purge air out of the first loop. I could not believe the amount of air in there. The problem is I let it run for over 20 minutes and there is still a substantial amount of air coming out. So much so that you can hear it running through the system. I tried the second loop only and same result. It has to be drawing in air from somewhere, but I pressurized everything to 30+ psi and waited over 30 minutes and it does not budge. I don't get it. The only thing I can come up with is the Wayne pump is sucking in air when it is running. It sounds a little funny to me and the priming plug does not screw in well.

Does anyone else use one of these that may have had a similar problem. If that's not it I am out of ideas. Any help would be great as I am ready to pull my hair out.

Gordy

It very well may be sucking air into the priming plug.
20 min purging one loop should do it. If your still getting air the pump is adding air to the purging water.
Your issues are an air problem with the wh.

GW

You gotta purge forwards and backwards at your wh. You need to pretend you're an air pocket, where would you hide from the guy trying to kick you out?

smuth10

One of the guys on the other forum stated that a spirovent will suck air when you are running a transfer pump if you do not cap it off. Is this true? If so I did not do this. I will feel like an idiot if this is the problem, but as long as it works...

GW

You're "sucking" with the transfer pump?

jonny88

Why dont you isolate the manifold and purge one loop at a time.Hook up hose to supply hose cock and run city water through it while draining from the return .

smuth10

I capped off the spiro and isolated the manifold and purged one loop at a time and then purged the entire system after this. The sprio was the problem drawing air into the system. It took an hour and a half, but all of the air is out. Unfortunately that did not solve my problem. I ran my pump by itself afterwards and as soon as I turned on the hwh it was reading .3gpm and would not turn on. If I restart it the hwh will turn on, but it only take a few minutes for it to go back down and shut off. I changed the psi to 25 and this did not help. The pump was working fine the first two days so I am not sure if i damaged something or what, but at this point I think I need someone to look at it for me. Does anyone know of someone in the SE Michigan area?

Gordy

quite possible the pump was running dry not good.

Gordy

It's a pretty simple set up all though the heat source would not have been my choice.
Did you try a different pump speed faster is not always better?
Are you sure the filter on the takagi is still clean after all that purging?

smuth10

I cleaned the filter and it starts up fine, but it had always done that after I cleaned the filter. Starts up around 1.7-1.8 gpm and then within a couple of minutes the vibration starts and it slowly goes down to .4 and shuts down. Is it possible the pump is not the right size or that the filter is the problem?. The pump says it does 0-17 gpm. Can I take the filter out at this point and just put in a plug to see if that helps?

I forgot to mention that I am having condensate problems as well. It is leaking out inside the unit right at the bottom where the outlet is and running over to where the gas inlet is and out the bottom

Gordy

In order to figure pump size you need to perform pressure drop calculations.

The gpm needed for the radiant

The longest loop, dia pex, pressure drop of hx at the required flow rate to satisfy the load.

Picking a pump is more complicated than going by 0-17 gpm rating there is a pump curve chart.

smuth10

I did do that at the beginning and that is how I came up with this pump. Will the water heater slow down the flow if it is unable to heat the water to 120 as it passes through?

Would someone here be willing to help me make sure it is the right size. Also, if I was to switch to a boiler, which one would you suggest for my setup?

Gordy

What is the longest length loop?
What dia pex?
What flow rate does your heat loss call for?

smuth10

I used the Hydronics Design Studio 2.0 to double check my numbers and the total BTU\Hr needed to heat my 30x40 shop is 5733 btu\hr.

GPM= 5733\(20x500) = .57 GPM flow needed.

The part I am a little fuzzy on is the head calculation. From what I have read it is the total length of pipe x 1.5 for fittings and then x .04. I have 1015 total ft of pipe with the 1000' of 1\2" pex under my slab. It calcs to over 60ft of head loss. That can't be right, so what am I doing wrong?

smuth10

300'
1\2"
.6 gpm

Do I only use the longest loop for the head calc. So it would be:

300 * 1.5 * .04 = 18

Gordy

I come up with 4.8' of head for the pex loop at .6 gpm 120*
And 11.55 ' of head for the takagi at 3gpm. That's 30% glycol

Total of 16.35' not including the near boiler piping.

That 1558 should do it.
That's the problem with these hot water heaters they have a very restrictive HX.

Plus,your using glycol that raises the head depending on percentage.

smuth10

After cleaning the filter several times I have it working on the medium setting at .9 gpm. It is still vibrating, but at least it ran all night. Thank you for your help everyone.

I may sell this thing and get a boiler. What would you suggest knowing my setup?

Gordy

What is the total heat loss of the building?

Have you taken the circulator apart, and checked for debris in the volute? Verify each speed is working?

This could simply be a circulator issue.

smuth10

The calc I came up with is 5733 btu\hr if that is what you are asking.

I have not taken the pump apart. I did take the filter out just to see what would happen and it went from .8 gpm on the medium speed to 1.6 gpm on the low speed.

Yes, each speed is working. Everything seems to be working now, but the vibration noise that is coming from the hwh is killin me. Ready to throw it out

Canucker

5733 btu/hr? For the whole building? I know nothing about the build but if that's correct, I need you to come up to Canada when I renovate my garage. I would love to be under 5 btu/hr for every sq ft. I don't think I could hit that even if I kept the garage at 35F.

GW

must have been a type-0, probably 3 or 4 times the heat loss at least.

I've never used a wh for radiant, I don't know the head loss through the hx (the wh).

Gary

Canucker

I've never used Hydronics Design Studio. Does it give a result based on the number of loops? That would make more sense to me, 5733 x 4 is a lot closer to what I would expect to see in my area, which I think would be similar.

smuth10

You guys are correct. I went back to double check my numbers and I did not have the correct sq\ft for the walls in there. What a jerk I am. Lol. The correct BTU\HR is 18,589. So with that being said it should be:

18,589/1000= 1.86 GPM

And according to Gordy I need around 16-18 of head and I believe the 1558 is capable of 19.5. Looking at it now after what I have learned this makes more sense. Now I just need to find out why the hwh is still vibrating. Could it possibly be glycol boiling like the manufacture told me? I only have the hwh set at 120 and I am only using a 30% solution.

Gordy

the chart for the takagi th3 says 5 psi pressure drop at 3 gpm. I assume 5x2.31 =11.55' of head plus the loop.

Gordy

Not sure about vibration issue may still be air trapped in HX.

Gordy

It would seem fan speed causes the issue you describe in the k3 models, or gas pressure.

Tim Potter

The pump is located on the outlet side of a restrictive HX, would the spirovent bleed air into the line when running on the 1558? The I&O shows the pump on the inlet side of the WH when used with an air handler. Has the condensate issue been rectified?

smuth10

I read about the TK3 fan speed issue and the tech had me turn on the dip switch that increases it and this did not help.

I also agree it sounds like air, but I have done everything I can to eliminate air. Any tiny bit left should be expelled by the spiro. Isn't that what it is supposed to do?

I have not tested the gas pressure yet as I do not have a pressure test kit. I have a 1" gas line run off of the 1.25" main in the basement as splitting off of the meter was not an option for me. The run is 75' and according to the charts I should be able to run a minimum of 140k btu's. I contacted the gas company and we did all of the calculations to make sure I could take on the extra load and they said I would be fine.

smuth10

No, the condensate is still leaking from time to time. The manufacturer sent me instructions and how to rebuild it myself to fix the problem. Thought this was a bunch of bs. It simply should not leak inside the unit imo.

smuth10

Here is the file they sent

Gordy

As Tim pointed out it may be worth a try to move the pump to the return side so you pump into the HX. of course that would mean moving the x tank also so you are pumping away from the PONPC. The air separator would stay in its present location.

GW

do you have a water line or no? run a hose through the wh and see what happens, lets pretend it's an actual wh for a few minutes.

smuth10

Why would moving the pump help? 1.8 gpm should be the same regardless of where it is at, no? What is a PONPC? Do you have a picture of the setup you would use or something similar? Everything I have read prior to the install was to have it located where it is. Granted this is on a DIY forum for the most part

No, it is a closed system and it was 19 out today so running a hose over is not an option as it is a detached building. I would love to isolate the hwh and test it, but it will have to wait until it warms up a bit

Gordy

PONPC is the point of no pressure change. The expansion tank. If you pump away from it the system will never drop below the set psi. The pump adds its differential to the system.

That's how circulators,work in a closed,system pressure differential.

So if the system psi is 20 pumping away from the x tank. the suction side will never drop below 20, and the discharge side might be 25 psi. This keeps air entrained to get back to the air removal device. Air hates pressure so it stays in solution.

If you pump into the x tank same system pressure the discharge will never go above 20 psi, but the intake will drop to 15 psi.
Air loves lower pressure it can then come out of solution. Causing issues.

For this reason pumping into a restrictive HX is better. Your raising the pressure going into it forcing air out of the heat exchanger. Also water has a harder time to boil the higher the pressure. Lower,pressure in the HX can cause water,to flash to steam.

That is probably why the I/O manual shows the circ pumping into the wh.