Need plumbers to critique hydronic radiant heating setup

[Ysleiro]

Hello there, a complete noob here.

I recently decided to implement Hydronic Radiant Heating in my house (NJ). I've read large portions of John Siegenthaler's book on the subject as well as consumed hundreds of hours on YouTube/internet researching.

I need people that are more experienced than me to critique this before I turn it on. I have a few questions.

1. Should I be worried about all these 90 degree turns. I often see plumbers complaining about 90 degree turns in plumbing loops. I need to know if that's something I should be worried about here.
   
   
2. I'm taking water from my hot water heater (Navien NPE-240S) and looping it though the heat exchanger using my primary pump. This water is then connected to the hot water heater's input line with a Tee connector. Note that incoming city water is connected to one end of that same tee. Will the city pressure allow the water I've pumped back into the hot water heater or will the pump be over powered by the city water and the pressure of the water the pump has already pumped?
   
   
3. I've placed the pressure relief valve on the incoming side of my primary pump. Should I place it on the outgoing side of the pump given that that line is connected directly to city water?
   
   

   Heatingsystem3

   • Ysleiro
   • Dec 10, 2019

   Diagram
   

   Entiresystem

   • Ysleiro
   • Dec 10, 2019

   Please read the comments in the picture.
   

   Top

   • Ysleiro
   • Dec 10, 2019
   

   IMG_20191210_133146_121019_014445_PM

   • Ysleiro
   • Dec 10, 2019

   Please pardon the typo. I mean to write "two".
   

   Untitled_Clipping_121019_014103_PM

   • Ysleiro
   • Dec 10, 2019

   City water supply.

 

[wood4d]

I will start... The pressure relief valve should be in the port on the bottom of the heater where they provided a spot for it. The pipe from the manifold to the heat exchanger needs to be bigger. Get rid of the bushing and make it 1".? The return line to the heater water supply needs a check valve and would be better on the pipe to the left so it doesnt have to feed in with a tee and then make a right hand turn or left. I dont see an aquastat to regulate temp and these systems do better pushing through the loops instead of pulling. Push after the tempering valve. Also I think you have a forced air thermostat which doesnt work with hydronics (maybe). I would put a pressure gauge on the water feed , not on the water main. I really dont have any problem with elbows and use them everywhere but am aware people think they restrict flow (but I like neat) I think expansion tank and bleeder are ok and you have a bleeder on the manifold too. I also dont use poly fittings for heat even though this is lower temp. There is a lot to look at in these photos.

 

[Ysleiro]

I will start... The pressure relief valve should be in the port on the bottom of the heater where they provided a spot for it. The pipe from the manifold to the heat exchanger needs to be bigger. Get rid of the bushing and make it 1".? The return line to the heater water supply needs a check valve and would be better on the pipe to the left so it doesnt have to feed in with a tee and then make a right hand turn or left. I dont see an aquastat to regulate temp and these systems do better pushing through the loops instead of pulling. Push after the tempering valve. Also I think you have a forced air thermostat which doesnt work with hydronics (maybe). I would put a pressure gauge on the water feed , not on the water main. I really dont have any problem with elbows and use them everywhere but am aware people think they restrict flow (but I like neat) I think expansion tank and bleeder are ok and you have a bleeder on the manifold too. I also dont use poly fittings for heat even though this is lower temp. There is a lot to look at in these photos.

Thank you so much. I acknowledge all your comments and will address them. Some of these seem to be no brainers now that you mention them. I've got a few questions though.

1) Aquastats are normally used within a tank no? I understand the purpose would be to limit the thermal inertia of the system so as not to cause temp swings and thus discomfort. Just don't fully grasp where I could place the Aquastat.

2) I'm currently pulling through my loop not pushing. I can easily change that however. You mentioned a tampering valve I've yet to add one to my system but from what I understand a tampering valve is a type of mixing valve? Would it work in conjunction with the acquastat to keep loop water at a certain temp? Where would you place the tampering valve?

The thermostat you see here is only for testing purposes. I have a proper thermostat capable of sensing temps in both ambient and floor.

I will upgrade all fittings to brass in due time. I'm approaching this system like I do software development. This is merely my BETA version. I'll be upgrading and updating as I learn and as the home demands.

 

[wood4d]

Sorry delete the word aquastat and insert tempering valve. My mistake. I put a pump behind the tempering valve, to push the tempered water. I dont know what type of flooring? material you are heating but you need temp regulation. It needs to be on the right side of the manifold. The only reason for pushing instead of pulling is that its easier to get air out. I hope you have the cleaning valve setup on the bottom of the water heater which is where the pressure relief valve goes. Its $100 and you will need it for servicing the system. You are using a 10 loop manifold which is overkill for what you are doing since you only have 2 connected. No issue with it but its just big.

 

[Diehard]

First off I would just like to say I have no real experience with Hydronic Radiant Heating systems.

I would however like to offer some comments/questions for you and/or @wood4d.

Regarding your concern for your primary pump being able to overcome that city water pressure will that recirculation water be the first in line into the water heater.
As I see it, it's a closed recirculation system between the heat exchanger and the water heater and with the absence of any simultaneous domestic water flow, there would be no problem. That loop would be at the same pressure as the city water pressure and the pump add some to get the recirculation. What bothers me is when the domestic water is in use, water has to also come from the city water source. This would effectively act as a tempering mix. I don't know how those self regulating on demand heaters will take to that. I got the impression, again not be really familiar those heaters, that they may adjust the flow to obtain the set temperature(?). Looking at the NPE-240S I see that the rated flow at 67 degree F rise is 5.6 GPM.
Have you or anyone figured out if this heater is the appropriate size for the dual application?
Have you talked to Navien at all about what your plans are and whether they have some guide lines for the dual function arrangement? I know it's not uncommon for them to be used this way.

Is the heating loop between the water heater and the heat exchanger is a closed system when domestic water is not being used? Or is there a way the expansion can be accommodated by way of the city water line? Which I assume presently does not have any device (PRV, backflow prevent, etc) that would prevent expansion back. Otherwise an expansion tank may be required.

Last question for now. Are those radiant heating system subject to any type of chemical additives? Most backflow prevention programs would require a double wall heat exchanger, as a single wall is not enough to prevent potential cross contamination with the domestic water side. As many people would think.

 

[Diehard]

I just read that note on your dwg that says, "

Is it still being used for domestic hot water? I had assumed it was.

 

[Ysleiro]

I just read that note on your dwg that says, "
View attachment 22679
Is it still being used for domestic hot water? I had assumed it was.

Correct it's still providing potable hot water. When I said "nothing" I was referring to the heating system. Some folks thought the water was being consumed/mixed with the water in the loops.

 

[Ysleiro]

Sorry delete the word aquastat and insert tempering valve. My mistake. I put a pump behind the tempering valve, to push the tempered water. I dont know what type of flooring? material you are heating but you need temp regulation. It needs to be on the right side of the manifold. The only reason for pushing instead of pulling is that its easier to get air out. I hope you have the cleaning valve setup on the bottom of the water heater which is where the pressure relief valve goes. Its $100 and you will need it for servicing the system. You are using a 10 loop manifold which is overkill for what you are doing since you only have 2 connected. No issue with it but its just big.

Understood on the tampering valve comments. The flooring is hardwood. The application will be underfloor in between joists.

I'll make note of the cleaning valve and temp regulation requirements (it's a tankless water heater by the way). I'm only using two loops currently but the plan is to use 7. I want to first get things working with these two loops/zones and then expand it to 7 ASAP.

 

[Ysleiro]

Yes friend. Agreed. Because my system won't be consuming water the pressure should not have any major fluctuations and thus the water coming back from the heat exchanger should have no problem making it's way back to the water heater (unless someone is consuming heated water in which case that's not a problem). I realized this after creating the post.

Have you or anyone figured out if this heater is the appropriate size for the dual application?

Truth be told I have not solved that part of the problem. We will find out I guess once I turn it on. I know what the heating load will be approx 40K BTU and the HWH is rated at 200K (given the ideal incoming water temp). The HWH also has an "commercial mode" that allows me to push the temps past 140 degrees. Although I don't want to go above 130. You think Navien will help me understand better if I speak to them?

Are you saying the HWH may slow the flow (GPM) if there is a call for heat from the kitchen in order to deal with the fact that some of the water being used to heat the heat exchanger will now be directed to the kitchen?

Is the heating loop between the water heater and the heat exchanger is a closed system when domestic water is not being used? Or is there a way the expansion can be accommodated by way of the city water line? Which I assume presently does not have any device (PRV, backflow prevent, etc) that would prevent expansion back. Otherwise an expansion tank may be required.

I believe it's an open loop; the water leaves the hot water heater and returns back from the heat exchanger past a "currently not installed check valve" to the input line of the hot water heater (is that an open loop? it sounds like it to me). I'm a noob but that's why in my plans I placed a pressure relief valve in the line that brings heat to the heat exchanger. The gentleman above has mentioned that the hot water heater should have a relief valve directly at its base however. I may add a backflow preventing pressure reducing valve near the point of entrance for the city water (do you think that's a good idea?).

Last question for now. Are those radiant heating system subject to any type of chemical additives? Most backflow prevention programs would require a double wall heat exchanger, as a single wall is not enough to prevent potential cross contamination with the domestic water side. As many people would think.

Currently it's just water. I have to find out if my heat exchanger is double plated (because I may make it a glycol mix in the future). Nice catch. Currently there is only one part in my entire system that is not lead free (I bought all lead free parts despite the system being closed). The Red expansion tank and the red port above it contain are not safe for potable water use. Do you think a single plate heat exchanger is good enough for that?

 

[Diehard]

A closed loop is a loop such as your heating loop where you have the expansion tank to take care of expansion and contraction.
So on that other loop between heater and heat exchanger, if that has no where to expand to it's a closed loop. If it can expand back through the water service supply it's an open loop.
Typically you don't need one on a tankless since the only time it heats up is when you run the water to a fixture. But when you create a recirculation loop it's being heated and cooled and must have someplace to expand to. or example if you put a Pressure Reducing Valve on that service, you would closing the loop.

AS far as double wall heat exchanger, that's depends on what your applicable cross connection regulations considers a hazardous material. I believe even with glycol, it may be acceptable as a non high hazard(non-toxic) if it was Propylene Glycol and NOT Ethylene Glycol.

As far as that red expansion tank, I believe the problem is that it might fail prematurely with chlorinated water. But it's in a closed loop so should be okay.

 

[wood4d]

the unit will have no issues with the demand. i have put many in. Now (per discussion) i think you need two expansion tanks one for the wh loop and one for heat. you also need to upgrade line sizes to handle the expected water load if you are adding 5 zones. you cant feed all that with a 3/4 line

 

[Ysleiro]

the unit will have no issues with the demand. i have put many in. Now (per discussion) i think you need two expansion tanks one for the wh loop and one for heat. you also need to upgrade line sizes to handle the expected water load if you are adding 5 zones. you cant feed all that with a 3/4 line

Are you referring to the lines from the HWH to the Heat Exchanger? the line that feeds the loops through the pressure regulating valve? or all the lines not part of the heating loops?

 

[wood4d]

The lines that are feeding the manifolds and returning flow to the exchanger. You need bigger piping or you are creating a dam. The line that feeds through the pressure valve is almost never going to be feeding water after it stabilizes. The lines fom the heater to the exchanger are going to limit the exchanger output to some extent but we dont know anything about the exchanger. You could use trial and error but around the manifolds you almost cant go too big. Its better to have a big supply of tempered water to distribute. It seems like you want to keep adding zones so maybe you want to go a combiboiler route. Taking some zones from this setup is one thing but if you are trying to create a new application you might look at what navien already figured out.

 

[Ysleiro]

Sorry delete the word aquastat and insert tempering valve. My mistake. I put a pump behind the tempering valve, to push the tempered water. I dont know what type of flooring? material you are heating but you need temp regulation. It needs to be on the right side of the manifold. The only reason for pushing instead of pulling is that its easier to get air out. I hope you have the cleaning valve setup on the bottom of the water heater which is where the pressure relief valve goes. Its $100 and you will need it for servicing the system. You are using a 10 loop manifold which is overkill for what you are doing since you only have 2 connected. No issue with it but its just big.

Back to this comment here. I'm a bit confused of the placement of the tampering valve. Because the heating loops are closed if I pull in cold water (from city line) to regulate the temperature of the water going out to the zones won't I be increasing the pressure of the loops which would trigger my pressure regulating valve to discharge water away?

I guess the question is where do I get cool water from? from the line coming back from the zone?

 

[wood4d]

The setup you are using (hopefully) only uses the refill/backflow setup if the system pressure drops. You are basicly using a closed system that never needs water except that never happens... Whatever forces act on the water in the syste, it needs replenishment somehow. The cool water you are using on the tempering valve is from the water that has transferred its energy into your house by heating it. Thats the cold line on your mixing valve (tempering valve). City water is only used to maintain the pressure. It is unused unless the system has a pressure loss. The cool line is the return from the radiant lines that have already spent their heat.