No/limited heating. Pictures included!

[StaceyQ]

Hey guys,

I have in-floor heating and noticed that it never really heats up completely. I checked the zone valves and they all seem to be working.

I touched the piping coming out of the boiler and noticed it was hot until it reaches a t-junction where it seems to run into the return line.

Going up from that t-junction, the warm water (marked by yellow) goes into each zone.

My question is if the hot water should be in a t-junction going into the cold water? It seems to defeat the purpose and that is where the water starts going from HOT to warm leading to only warm water getting into the zone.

Please let me know if it's normal and if/how I could fix it.

[donk.]

Tap the recirc pump with your hand to make sure it's not hot (burn), then put your hand on it, it should be vibrating, during a heat call to at least one of the zones.

There should be an arrow on the red body of the volute assembly (back of pump), make sure this is pointing up

Pipe temperature on the discharge of the pump, and coming out of the boiler, should be similar, assuming the pump is on

Depending on how the thermostat is set up, it may very well be set up for an outdoor reset system.
Colder day = hotter supply
Summer day = probably 0 output
In other words, you will never feel hot piping, unless it's -10C outside.
Above is an assumption

Edit: what is the pressure of the system? Gauge on bottom left of boiler
Are there any heating zones above the height of the boiler? (2nd / 3rd floors)

[SSM_DC5]

Originally Posted by donk.

...
Are there any heating zones above the height of the boiler? (2nd / 3rd floors)

What if the answer to this is yes?

I have some cold zones that feel the same temp as outside and the questionable zones are 2nd and 3rd.

[donk.]

@SSM

If the answer is yes, and the pressure in the system is less than 1psi per 2.31ft, then it's a problem

Ex, 2 story house, height of second floor, in floor heating is 11ft.
11ft / 2.31 = you need 5psi minimum.
Or 21ft (3rd floor), 21 / 2.31 = 10psi minimum.
Assuming the gauge is not faulty

Furthermore, you may have air vents that are airlocked, these need to be bled out. (Same as your car radiator loop, highest points may get airlocked)
Manual air vent = open till there's no air, if your unlucky, the gasket is gone and it will not re seal
Auto air vent = probably failed, or the 1/4cap has been tightened, loosen 1 turn, wait till it stops hissing, close back up

Or you have a couple of rats that made it into your closed loop heating system

[StaceyQ]

Originally Posted by donk.

Tap the recirc pump with your hand to make sure it's not hot (burn), then put your hand on it, it should be vibrating, during a heat call to at least one of the zones.

There should be an arrow on the red body of the volute assembly (back of pump), make sure this is pointing up

Pipe temperature on the discharge of the pump, and coming out of the boiler, should be similar, assuming the pump is on

Depending on how the thermostat is set up, it may very well be set up for an outdoor reset system.
Colder day = hotter supply
Summer day = probably 0 output
In other words, you will never feel hot piping, unless it's -10C outside.
Above is an assumption

Edit: what is the pressure of the system? Gauge on bottom left of boiler
Are there any heating zones above the height of the boiler? (2nd / 3rd floors)

The arrow is pointing up.

I have the thermostats in the houses cranked and the zone control manual overrides are loose (which I assume means they are working and hitting the end switch to call for heat?) and there's no noise or hum out of the pump. The pump itself is warm and I have tested that there is power going to it. The pump itself is warm, not hot. Can't tell if it's supposed to hum or whirr.

The pipe is cool/warm at/from the t-junction, past the pump, and into the zones. Is it normal to have the hot water run into a T and mix with the cold/return?

The upstairs is definitely cooler than downstairs. Maybe the pump is on its last legs?

Pressure is about 18PSI (picture attached).

[donk.]

@Stacey

The pump should have a minor vibration to it, hard to tell unless you handle them regularly.

If the power matches the nameplate rating, (leg to leg, not to ground) I would suspect the motor is seized, the impeller has disintegrated, the impeller is stuck to the volute.

Depending on your level of DIY, you can turn off the pump, close the supply valve to the pump, plus all zones. Then loosen the 4 Allen key bolts holding motor to the volute. Wiggle the motor off, drain the pressure until it stops, then fully remove it.
At this point you can turn the power on to the motor only, and verify if it actually spins.

Ps, the gauge is faulty, I doubt the heating temp is 260F. It may be possible that the 18psi is actually xpsi
Furthermore, just because there is pressure, does not mean there is flow

I could be wrong on all of the above, this is just what I see based by information provided over the eeeenternets

At this point, I would personally recommend you call out a professional, Incase things don't reseal, or leak, or you need to further diagnose.
4hrs labour, bill should be sub 500$ for a repair assuming no parts need replacing

[StaceyQ]

I may try to remove the pump and see how it goes.

I guess I'll have to refill the close loop system? Or does it auto refill?

[donk.]

The rusted PRV on the top left of the green expansion tank will auto fill the system.

You may, need to bleed air out of the system after doing the pump in/out. Unless there is an air bleed ontop of the actuator manifold. (Picture is cut off)

[SSM_DC5]

These are my auto air vents, the one at the back has no tiny cap on it.


getting 15 or 16 psi


I haven't seen any where I can manually vent from on the upper floors.

And here's a pic of the whole system incase it helps

[HKS PWR]

1) First things first, determine if there is circulation of water in the zones. If the zone valve is open the water should go through that loop and come by via the return, which should also be warm/hot. If there is no circulation it would mainly be the circulator (pump) and/or air lock (more common on the upper floors). Try bleeding/flushing each loop to get rid of the air.
2) Won't be the outdoor reset because a) this older navien combi boiler didn't have outdoor reset and b) outdoor reset doesn't stop making hot water for hydronic heating. The whole point of the outdoor reset is that it changes the heating curve (for example if it was -10c outside, it would produce water at 140f for in-floor heating. If it was 10c outside, it would probably make it at 100f to save energy)
3) I'm not sure if that Honeywell circulator (pump) has it, put the Grundfos circulators has a removable cover on the housing that cover the shaft. You can remove it and see if the shaft is spinning without disassembling the circulator (be careful since these are wet rotor circulator meaning some water will leak out). FYI chances are if the circulator is seized and not spinning, the housing of the circulator would be too hot to touch.
4) That "T-junction" that you're asking about is "correct". It's one of the ways to pipe these high-efficiency boilers with multiple circulators for hydraulic separation. I say "correct" because it's technically not configured correctly, but still kind of does the job.
5) These older Navien combi boilers do not produce output for both domestic hot water usage and space heating at the same time. The 3-way valve prevents that and will prioritize domestic hot water production, meaning if someone is using domestic hot water, it will not make hot water for space heating.
6) Should really call a heating tech. Good luck getting one to show up right now since everyone turned their heating system on for the first time this week and found out it does not.

[StaceyQ]

Update!

Boiler was messed up in various ways (leaking, wiring...etc). Navien replaced it underwarranty (phew!) but it still cost around $3.8k to get the system installed and piping fixed/other misc things. HKS PWR was pretty much spot on in his diagnosis. I used Coppersmith plumbing (run by a guy named Jackson). Dude's legit and honest.

But more importantly, here are the pictures.

[punkwax]

+1 for Jackson.

Reminds me he has a little job left to do at my place as well.. obviously nothing urgently needed but thanks for the reminder nevertheless.