NTI Boiler and HWH Help

edge70

Hi there, I have NTI TFT Boiler paired with a NTI S65 HW Heater. The Boiler seems to be calling for DHW constantly and I can see that the relief valve on the HWH is purging a steady stream of water continuously. I don't believe this is correct and it would be nice to get this fixed up. Note, our boiler runs some in floor heating zones (non are currently being used as it's not cold yet) as well as our DHW. Note, DHW does our hot water tank and it also will go to a heat exchanger to heat our pool in the summer. This has recently been shut off. Any thoughts? Could it be as simple as a new relief valve?

EdTheHeaterMan

Not enough info to answer your query. But I would definitely replace a leaking relief valve if it is defective. However, if the relief valve is not defective, and water is spurting as a result of overpressure, the valve is working as intended. I would fix the overpressure problem and then see if the relief valve stops releasing water.

Note: DHW is an abbreviation of Domestic Hot Water... so DHW is supposed to DO your water tank that stores the Domestic Hot Water.

STEVEusaPA

Unused, relief valves rarely fail. Once they start doing their job something else is wrong. And of course they just wont seat right, usually requiring replacement. But that happens all the time because once a year we exercise it...right?
Like Ed said, gonna need to see some pictures.

Tom_133

If its calling all the time most likely you got a wiring issue, or a bad aqua stat. It wont take long to remedy once you throw some pics on here.

edge70

I turned off the cold water feed to the how water tank and I could hear a noticeable drop in sound (hissing) from the relief valve. It did still leak a bit but not as much and the pressure sounded much less. Also, I could see the hot water temp for the HWT on the boiler HMI rise fairly quick. Once it hit 140F the demand shut off and the boiler stopped.

My theory is that relief valve is dumping so much water that it's not staying at temp very long and the boiler is constantly modulating in order to keep up.

I'll post some photos....

edge70

Tom_133

Oh my where to begin... the two wire nuts tied to your supply pipe on your water heater, if you follow that does one end go to an aqua stat?

Im not sure all thats happening here, but this looks like a chop and swap from hades, not being mean or insensitive but you got a lot of issues happening here

edge70

@Tom_133 Yes, that's exactly where they go and from there, the LVT wire runs back to the boiler. I'll post a couple more photos. Note, I appreciate brutally honest feedback. It's a fair size home with lots going on here... We are in Canada so the winter can be cold and the wife and kids appreciate it when the heat works

edge70

Tom_133

so the screen on your boiler should say the tank temp, whats the screen say for "DHW"?

edge70

It stays around 140F

fenkel

.check the aquastate, it doesnt appear to be securely held in the aquastate well.. id take that aquastate out and put some heat paste in the well,  then reinstall the probe so that it reads better . put a better well clamp on it to secure the probe in the well..
Id also think about replacing that probe as well... i just looked closer at picture..one wire appears to be broken.
That could cause your tank to over heat and blow the relief valve. It could also cause poor heating of the water in the tank...it could even send faulty water temps sent to boiler...
We have a general rule in the shop." if it leaks..its gets replaced as soon as possible!".. you  wouldnt want the basement to flood..

BillyO

Check the pressure on your thermal expansion tank, make sure tank pressure matches incoming cold water pressure

Tom_133

if the screen is showing 140 and there is still a call for hot water, you got a control problem. If as you say you are losing a lot of water and its just maintaining tank temperature, then for sure change the relief valve, and as was mentioned, check that potable expansion tank.

edge70

Thanks for all the suggestions guys. Much appreciated. It seems odd to me that even when I close the valve for cold water to the HWT, the relief valve still leaks a bit of water. Not as much but I wouldn't expect any to leak then as there isn't much pressure in the tank at all.

When the boiler reads 140 from the HWT for a minute, the call for DHW goes away and the boiler goes into standby. When the HWT eventually drops to 135, the boiler comes back on and reheats the tank. Should I drop that value to 130F so that it cycles less often?

At this point I suspect that the relief valve is bad but I'll check out that sensor as well to ensure it's functioning as intended.

mattmia2

It is the hot water tank relieve valve that it tricking, not the boiler relief valve, right?

edge70

@mattmia2 Correct, the hot water tank relief valve. Boiler relief valve has no issue.

hot_rod

Do you have a pressure gauge on the potable water system anywhere? is it possible your water pressure is excessive? Are you on a public water system? Have a pressure reducing valve?
Looks like a DHW ThermTrol tank, so I assume you have public water and a back flow device?

edge70

@hot_rod Yes, I'm on city water here. I believe our pressure is pretty high but I don't think we have a pressure reducing valve. The expansion tank is on the cold water side of our system and I believe it's meant to be a top up for the boiler when needed. We do not have an expansion tank on the Hot Water tank. I remember that as soon as this tank was installed, the relief valve leaked a bit and the HVAC tech thought it odd. They said it wasn't anything to worry about but no it's gotten much worse. I'll see if I can find a way to get a pressure reading on the cold water feed to the house or at least on the cold water feed line to the hot water tank. Thanks!

hot_rod

The expansion tank in the picture looks to be a DHW ThermTrol? It could be the boiler is using that tank, if it is the only tank in the room?
If you are on public water there is a good chance you have a back flow device, it could be at the meter or in a meter yoke.
Most all water heaters these days need a thermal expansion tank, as you could have a back flow device added by the water provider and you may not know it.
I think most plumbing codes require a thermal expansion device, either a tank or valve.
In your case the thermal expansion device may be your relief valve. How much do you pay for water, since you are running quite a bit down the drain as that valve discharges or seeps

edge70

@hot_rod Yes, this is a thermtrol expansion tank and I'm certain it's for the boiler. The water line runs from this to the manifold that has all the pumps for the various in-floor heating zones. Prior to the water entry of that thermtrol tank, there's another valve couple valves. One has a drip in it now... just recent. See photo:



Here's a photo of the main water line entering the house and the shutoff valve there.



It might make sense to have an expansion tank on the hot water tank as well then.

Henry

Most tank manufacturers require an expansion tank on the cold water inlet to the tank. BTW I have not seen such a bad install in some time.

EdTheHeaterMan

I like to solve wiring problems more than water pressure problems but... I see 2 things here that are of concern.

1. The relief valve that is leaking has 2 functions, temperature (210° one-time failure) and pressure (150 PSI multi - and manual) release. So at this point, if the valve was operated manually at some point (as recommended by the manufacturer) there is a possibility that the seat has some debris and therefore defective and should just ve replaced. That is where I would start. That may be your only issue. these valves are inexpensive enough and can be professionally replaced or DYI. No big deal.

2. The expansion tank "for the boiler" is incorrect and should be checked. The tank is designed by the manufacturer for DHW open system use. It, therefore, has a higher factory set air pressure in it. If the installer did his job properly, he would have reduced the pressure to the desired boiler static pressure (of maybe 12 PSI) before commissioning said tank. A tire pressure gauge would let you know. There is a trick to properly testing an expansion tank air pressure. See this post: https://forum.heatinghelp.com/discussion/comment/1610522#Comment_1610522 for more info on properly testing expansion tanks

hot_rod

Some installers like to use those ThermTrol tanks on pex radiant systems due to O2 ingress. Amtrol actually makes a -R radiant tank that is basically a ThermTrol with a 1/2" connection.

Could be a backflow device out at the connection to the water main. Some areas have meter pits out front with the BFD in the pit with the meter.
Speaking of backflow devices, the small one for the boiler should have the vent port facing down, and it should be piped to a drain as they do spit occasionally.

The green scale around it indicates it may have discharged a few times. that too could be from excessive main water pressure and hydraulic shock caused by fast acting valves, washers, etc. A thermal expansion on the water heater helps that as it acts as a water hammer arrestor also.

edge70

Henry said:

BTW I have not seen such a bad install in some time.

Can you please advise on why this is a bad install?

fenkel

Ive seen a lot worse than this...
But, Some of the supplies used make  it look shoddy.

edge70

@fenkel Would some of the supplies in question be the mixing valves on each zone and the black iron pipe?

fenkel

Not to be picky. One grundfos pump is installed incorrectly..per the  install instructions: the pumps electric box, shouldn't be on bottom of pump..sure it works,but what happens if the pump leaks??  Result is pump shorts out and shut system down..
The pipe fittings  seem painted .why?
They wouldn't happen to be galvanized fittings? 
The use of plastic pipe and rubber hose on water heater look at best hokie...
Im not a big fan of the aluminum gas line.
The use of the wrong expansion tank.
The one  in picture would be better on the water heater. 
I dont see a mixing valve on the water heater..
Is there a drip leg on gas line?
Id also hard pipe  the waterheater as well.
Not sure if oxygen barrier tubing is used...
 Alot of the pipes have  rust stains on them.. leaking? You really dont want any leaks..leaks are long term problem markers .
The intake and exhaust lines appear to touch each other and not property secured..
Now if you paid a contractor to do the work..its not up to standards..
If you hired a craigslist contractor..well thats what you sometimes get..
If your a dyier,it needs some help..

Id recommend you have the relief valve replaced on water heater,  next have a correct expansion tank installed on cold line to water heater and on boiler
Have the expansion tanks set to the correct pressure.
The backflow preventer is on which supply line?  I'm not that impressed with backflow preventers, most leak..
I might use a swing style check valve before the cold water expansion tank..
Id next install a mixing valve on water heater and set it to 120 degress or lower to prevent anyone from being scalded.

edge70

@fenkel, thanks for the detailed comments. The work was done initially by a licensed HVAC contractor but they are less than impressive... Originally they installed a weil mcClain boiler and that only lasted about 8 years which seems odd to me. Since then, I've had another guy help fix up some of the initial work. In fairness, he walked into a bit of a mess.

The rust I believe came from a bit of water when the recently replaced the zone pump for the heat exchanger I use to heat our pool.

I'm going to ask them to implement the changes that you guys have suggested. I could change the relief valve myself but there's a recall on the boiler anyhow so they are going to do that work.

Thanks again.

fenkel

Some boilers only last that long...
I have a suspicion that water quality might have been a culprit in its early death.