Radiant Heat Loop Not Working #2

hot_rod

Thanks for watch the trainings, nice to hear they are useful.

I think a combination of issues with this system.

Pumping at the expansion tank could be part of it. Without defining the entire piping, hard to predict. If the fill pressure dropped low, it could be under sub-atmospheric conditions in part of the circuit.

The old Series 100 didn't develop a lot of ∆P and got away with pumping at the PONPC. Any wet rotor, higher rpm, larger impeller, even medium heads often turn up new problems with those "pumping at" systems.

Checks of any sort should never be on the inlet, potential for cavitation, but combined with the wrong PONPC it could be part of the deal.

Most circs, even small ones, want a bit of positive pressure, higher pressure at higher temperatures. Some manufacturers publish that suggested pressure.

If that is a ASSE 1070 valve, it has a max setting of 120F.

I would still pipe a true P/S if it were me, move the exp and add a real air separator, but..

Ralphxyz

Damm, went to the supply house and got some 1 1/4" pipe and some fittings. It cost me $95.00, course I am paying retail no longer have my trade accounts and discounts.

STEVEusaPA

hot_rod said:

Thanks for watch the trainings, nice to hear they are useful.

Understatement of the year!! They are awesome, as well as Idronics. It's the only mail I look forward to receiving.

Ralphxyz

Well I did the first step, replaced the Tee:
At the boiler:


At the mixing valve:


Guess what???

Does not work!!! no difference!

The Grundfos UPS 15-58 FC are looking better and better.

Ralph

Ralphxyz

I remembered that I had picked up another 24" pipe wrench at a yard sale.

Luckily I remembered how to remove a plug that had been in place for years, that plug would not have move with a 6' wrench.

The 1 1/4" st. ell was strange, it jammed up tight on two or three threads, even with a cheater bar I had to heat the Flow Check to get the st.90 to where it needed to be, luckily I go it to the correct place and was able to add the 3' pipe.

Geesch this has been a royal pain.

Thanks for all of the help, will be at page 5 before we are done.

Ralph

Jolly Bodger

does it work again if you open the flow-check like before? Not sure what that would mean exactly. Just wondering.

GroundUp

Had anyone considered that B&G does not list a 3 pipe connection as an option because it's not designed to work that way? Guess not. 2 ports are to be used, the 3rd plugged. RTFM.

The radiant friction loss is roughly 3.5ft of head. The 15-42 is capable of 14.5 ft at the 1 GPM the radiant is flowing. A 15-58 would raise that only to 19. I honestly can't believe this is still going on. You guys crack me up

STEVEusaPA

I initially commented on these 2 threads, as did others and simply said it wasn't piped right. It probably still isn't piped right, and if the OP does get it to work, it will be by dumb luck.

I am amused by the thread which has gone from DIY to DIWhy?

When troubleshooting a problem like this, before I would even think about changing the piping or the circulators I'd pull out a pencil, pad, ruler and a calculator.
It's never worked right from the start, and all the 'try this, try that' advice is kinda poor troubleshooting technique.
Some of the best in the business have dropped out because they know they are wasting their breath.

You need to pay to have a qualified hydronics pro come visit the sight, look it over, redesign your system based on best practices and calculations (math).
Then you can do all the rest yourself.

Jolly Bodger

I'm having fun here. It's like a laboratory where I don't have to do the work or pay for the parts.
Anyone could tear it all out and rebuilt it from a diagram. But we would't learn anything that way. Those diagrams were developed by learning lessons this way.

Ralphxyz

Actually I "think" my two options are to put a spring check valve below the house circulator and open the Flow Check or install one or posible two Grundfos UPS 15-58 FC circulators.
Who is a "qualified hydronics pro"? I thought you guys were.
But a really BIG THANK YOU to all that have tried to help.

Ralph

Ralphxyz

Problem was the Circulator was air bound

Click on the image to hear it, the circulator surging.

So now it works! But it is real slow. The supply is hot but after a couple of hours the return is barely warm. This is even with the house circulator running, it used to be with the house circulator and radiant loop circulator running the return would get hot.

I am looking at the circulator pump curve and getting confused.

I have 19 psi (43.82' of head) at the boiler.
The Grunfos UP 15-42 curve peaks at 11 3/4+' of head 0 gpm.

The TACO 007 peaks at 9.75+ ' of head 0 gpm.

Do I (how do I) need to lower the boiler static pressure?

Thanks, for the much need help!

Ralph

GroundUp

Once again, static pressure has NOTHING to do with head/friction loss in the system. All that means is you could push water up a 43.82 ft column with 19 psi at the bottom- nothing else. As I said before, your friction head is approximately 3.5ft through the radiant. Maybe add in another 2.5 for the mixing valve and piping. Low flow = low friction loss. Also I don't know what curve you're looking at but a 15-42 will produce 14.5ft of head at 1 GPM. Please remove the circ from this equation, it is not and has never been an issue. But did you seriously just ask how to lower pressure in the boiler?

HomerJSmith

Perhaps, a review is in order. The boiler water is never under 160F because of the tankless coil. Ralph want to use this heated boiler water to heat the radiant circuit when the house heating circuits are not calling for heat. So, flow to the radiant circuit must pass thru the boiler. The house heating circuits flow must pass thru the boiler. These two flows must operate singly or in tandem.

P/S system would require major re-piping with some control of the house heating circuits.

Part of the house heating circuit is currently used with the radiant circuit. There isn't any hydrolic separation between the boiler pump and the radiant pump as it is presently configured. The only effect is when the boiler and radiant pumps are running at the same time. That would increase the flow as the pumps are in parallel.
The RTI would restrict the flow thru the boiler circuit.

The 15-42 is going to pump 14.5'hd @ 1 g/m thru a combination of the boiler circuit and the cold input to the RTI unless there is a bottle neck somewhere or the 15-42 runs out of head energy.

GroundUp, thinks that the 15-42 is adaquate in terms of pumping power. If that's the case than I think there must be a bottleneck somewhere. One only knows if the 15-42 has adequate pumping power is by doing a pressure loss calculation on the radiant circuit.

I thought the RTI (CV=1.9) was the bottleneck and suggested to replace it with a Taco i-Series set point mixing valve that has a high CV. It is sensor controlled rather than a wax pellet and runs on 24V rather than being passive. Is that the cure, I don't know. It would certainly give a boost to the 15-42.

I don't see any problem with taking off the radiant circuit from the flo-check plugged outlet. It wouldn't be any different than taking off the radiant circuit from anywhere before the flo-check.
It is just a pass thru. The reason that the manufacturer doesn't have it as a listed option is because there is never two supplies to it and it is practically never used as a pass thru. All it is, is a tee with a weighted plug on the output.

The radiant circuit operated when the radiant pump was operating with the boiler pump. What does that tell you?

Jolly Bodger

@Ralphxyz might want to pause for a second and take a diagnostic approach. What has changed? Did it work well before repiping, just opening the flow-check? Repiping to the flow check should not have increased the head resistance. You found the pump air locked. Are you sure the PEX loops are not air locked or the return line to the boiler?
A agree with @GroundUp the 15-42 should be plenty of pump.

hot_rod

If it is a 1.9 Cv valve, possible if it is a 1070 listed valve.
We know has 2- 1/2 loops around 250 feet according to the drawing somewhere in this thread.
Assume .75 gpm per loop, here is the pressure drop.

This Excel can solve an unknown if you have 2 numbers
∆P across the circ, and cv of valve plugged in, for instance would give you the actual flow rate.

Cv and flow rate (assumed to be 1.5 gpm) gives you pressure drop.

I doubt installing 15-58s is going to fix the glitch.

Ralphxyz

As of the moment taking the radiant loop supply off the back of the Flow Check is working!
The room is being heated very nicely, I am playing with thermostat settings to get the correct heat, at times the room is too hot.

Thanks again, this has been so interesting and very informative discussions.

Ralph

GroundUp

Have you considered setting the thermostat to the desired temperature and leaving it alone? That's kinda what they're for. If the room overshoots setpoint, the supply water is too hot

HomerJSmith

Ralph, GroundUp is right. Set the thermostat and forget it. Infloor is a very slow to heat up and very slow to cool down. The heat emitter is the concrete not the tubes embedded in the concrete. It takes time to heat up the concrete and time for the concrete to cool. Infloor is a high mass system.

The heat to the pex is regulated by the RTI. The mixed flow to the pex should be less than 100 degrees/F. Adjust the temp.

The RTI regulates the temperature. It doesn't regulate the flow. Flow has a lot to do with the temperature delivered to the floor. When the boiler pump is operating with the radiant pump the flow changes and could result in variation in the floor temp.

I would recommend a pressure balancing valve such as the Caleffi 3/4" NPT QuickSetter Balancing Valve w/ Flow Meter. The flow can be set without an instrument. I'm not sure where I would mount it. Between the pex manifold return and the cold water feed to the RTI or whether it should be mounted between the cold supply tee to the RTI and the tee at the boiler pump output? This would set the flow to the radiant circuit and actually help the boiler pump deliver a better flow to the baseboard circuits.

I can see that if the radiant pump and the boiler pump are both running, the radiant pump would add flow to the baseboard circuit. I don't know if this make sense.

Be sure and change the location of the expansion tank, tho.

Ralphxyz

Thanks again, I like to set back the thermostat at 11:00pm to 62°
and then start the day at 5:00am at 70° with a setback to 65° at 9:00am leaving the setting at 65° from 9:00am until 11:00pm is working very well. So for the most part of the day I do not change the settings.

It does not appear that the house circulator is having the impact that it did with the previous piping. I wish I had data logging instruments to real nail the operation.

It works! why would I move the expansion tank? Theoretically moving the expansion tank to the return side might be optimal but hey it works now what would be the gain of moving it?

Ralph

Jolly Bodger

As long as it works and you are comfy.
62 to 70 is a huge Jump for hydronics. I don't even set back my commercial forced air buildings below 65. And when is comes to concrete slab infloor it is probably not even possible to swing it that fast.
But as long as you are comfy, run it how you want.

Ralphxyz

Even though I start at 5:00am at 70° it never actually gets to 70° before the 9:00am setback to 65°. It works well!

Jolly Bodger

Yep, you are basically turning a switch on. I understand completely. Just the fact that is is actively heating is enough. Especially if you are talking about the infloor. Toasty feet!
Glad this is working for you know.

Ralphxyz

Checked this morning at 9:30am and the room was at 71° so it is really working well!