Navien 210A on radiant heat system, gpm falls every day

Users who are viewing this thread

Jjaslow

New Member
Messages
6
Reaction score
0
Points
1
Location
W. Milford
We just moved into an older home with a radiant heating system. The seller just replaced the heater with a brand new 210A heater. I had a plumber come in to service. He said that the gpm should be around 3, and he set the outgoing temp to 160. Ive read thats a bit higher than recommended, but he said it was common for a staple up system like we have. When he left, the gmp was indeed at 3, but over the weeks, Ive noticed that it drops a bit every day. Over the weekend, it was around 1 GPM, and the house was much colder.

A few days ago I reset the system myself. By that I mean that I turned all the pumps off for 30 minutes and also pressed the reset button on the heater. When I turned everything back on, I was happy to see the gpm back to 3 and the heat was much better. But now, only a few days later, the gmp is down to 2.4. Is there something I can do here?

thx,
J
 

John Gayewski

In the Trades
Messages
2,941
Reaction score
789
Points
113
Location
Iowa
We just moved into an older home with a radiant heating system. The seller just replaced the heater with a brand new 210A heater. I had a plumber come in to service. He said that the gpm should be around 3, and he set the outgoing temp to 160. Ive read thats a bit higher than recommended, but he said it was common for a staple up system like we have. When he left, the gmp was indeed at 3, but over the weeks, Ive noticed that it drops a bit every day. Over the weekend, it was around 1 GPM, and the house was much colder.

A few days ago I reset the system myself. By that I mean that I turned all the pumps off for 30 minutes and also pressed the reset button on the heater. When I turned everything back on, I was happy to see the gpm back to 3 and the heat was much better. But now, only a few days later, the gmp is down to 2.4. Is there something I can do here?

thx,
J
Sounds like air to me. Do you have an air separator?
 

Jjaslow

New Member
Messages
6
Reaction score
0
Points
1
Location
W. Milford
No air separator yet. Speaking to a plumber about adding one.

20220117_125805.jpg
 

John Gayewski

In the Trades
Messages
2,941
Reaction score
789
Points
113
Location
Iowa
No air separator yet. Speaking to a plumber about adding one.
After some time with an air sep the gpm shouldn't really be variable unless the pump is bad or your switching between different sized zones.
 

Fitter30

Well-Known Member
Messages
3,135
Reaction score
506
Points
113
Location
Peace valley missouri
City water is constantly feeding the heating system and suppling dhw? Thats what it looks like. What u have is called a open system where city water is used for heating and dhw. Where in the off season water is stagnant in heating system. What brand and model of return pump? Zone pumps didn't see any check valves? Complete of model of boiler?
 
Last edited:

Jjaslow

New Member
Messages
6
Reaction score
0
Points
1
Location
W. Milford
City water is constantly feeding the heating system and suppling dhw? Thats what it looks like. What u have is called a open system where city water is used for heating and dhw. Where in the off season water is stagnant in heating system. What brand and model of return pump? Zone pumps didn't see any check valves? Complete of model of boiler?

All 4 pumps are brand new Grundfos 3 speed pumps. I have the primary loop set to high and the 3 secondary loops set to medium.

There are check valves on the primary loop and 2 on each secondary loop, one after the pump and another right before the loop connects back to the primary loop on the return side.

Its not a boiler, but a Navien NPE-210A hot water heater.

thanks,
Jason
 

Fitter30

Well-Known Member
Messages
3,135
Reaction score
506
Points
113
Location
Peace valley missouri
Air separator will do no good with water constantly entering the system bringing in entrained air. Your flow in changing because when a zone or zones are calling incoming flow through heater is changing. Zones not calling what is shutting system pump off? Pump come on with dhw? Don't need two checks around pumps just one on discharge.
 

Jjaslow

New Member
Messages
6
Reaction score
0
Points
1
Location
W. Milford
Air separator will do no good with water constantly entering the system bringing in entrained air. Your flow in changing because when a zone or zones are calling incoming flow through heater is changing. Zones not calling what is shutting system pump off? Pump come on with dhw? Don't need two checks around pumps just one on discharge.

Thanks for the info. Not sure I fully understand everything you are asking. We have 3 thermostats around the house, and the relevant pump turns on when the thermostat wants it. I have noticed that the flow decreases over time, regardless of the # of pumps on. After my last 'reset' (ie turn all pumps off for 30 minutes) the flow goes to the expected 3.0 regardless of how many pumps are on. But that number decreases over time no matter how many pumps are on.

Here is the proposal I have from my local plumber to 'fix' the system. Its supposed to prevent the heating water from entering my dhw among other things:

Current system is operating as an open loop high pressure system. We will provide the following components to convert the current system to a low pressure closed loop.
1- 11/4 Spiro vent and associated fittings
1- #30 expansion tank complete with back flow preventer and pressure reducing valve.
1- isolation valves
Misc 11/4", 3/4" and 1"
 

Fitter30

Well-Known Member
Messages
3,135
Reaction score
506
Points
113
Location
Peace valley missouri
This piping will separate heating loops from dhw with a 200k btu heat exchanger, air separator, expansion tank and couple of added pumps.Where is w milfdom?

IMG_20220130_121408.jpg
 
Last edited by a moderator:

Terry

The Plumbing Wizard
Staff member
Messages
29,939
Reaction score
3,400
Points
113
Location
Bothell, Washington
Website
terrylove.com
West Milford, New Jersey
I think he just misspelled it, I noticed it right away, checked it and saw that the spelling was close enough.

West Milford is a township in Passaic County, New Jersey, United States. As of the 2010 United States Census, the township's population was 25,850, reflecting a decline of 560 from the 26,410 counted in the 2000 Census, which had in turn increased by 980 from the 25,430 counted in the 1990 Census. Wikipedia

west-milford.jpg
 
Last edited:

Jjaslow

New Member
Messages
6
Reaction score
0
Points
1
Location
W. Milford
Ah, yes. Now I see what you mean. Terry is correct. I have updated my details. Sorry for the confusion and thank you again for your help. ;)
 
Top
Hey, wait a minute.

This is awkward, but...

It looks like you're using an ad blocker. We get it, but (1) terrylove.com can't live without ads, and (2) ad blockers can cause issues with videos and comments. If you'd like to support the site, please allow ads.

If any particular ad is your REASON for blocking ads, please let us know. We might be able to do something about it. Thanks.
I've Disabled AdBlock    No Thanks