Navien ch-240. Too much pressure.

bwdh20

I have a Navien ch-240 combination heater.

I am getting too much pressure into the machine. Blew the 30 psi relief valive and with a higher psi relief the machine reads 58 psi.

Rich_49

Got a picture of the unit and near boiler piping and accessories ? These would help .

4Johnpipe

Is this a new install? 58 PSI is pretty standard city water pressure. Is there a pressure reducing valve?

JStar

Please don't put a bigger relief valve on. That is incredibly dangerous. Put the 30psi valve back on immediately, or shut the system down and call a competent technician to work it.

Xmytruck

Make sure you report which pressure valve went off the direct hot water should be 150psi. The space heating should be 30 psi, if that's the one that went off you most likely have a bad expansion tank shake the tank to tell if it waterlogged. Must have been cold if you turned your heat on in Aug.


my direct hot water pressure valve on my NCB 240 went off last week but the town has been messing with the water pressure. Had a plumber check it out he basically tested the valve and gave it the thumbs up.

njtommy

Could be a couple of things.

I believe the CH-240 has a make up water valve built in to the unit and controls its own pressure from there.

If your water make up, is piped external of the unit in a more traditional boiler set up I would say bad expansion tank.

I would also look into a cracked heat exchanger where your boiler water and domestic hot water are now mixing together.

bwdh20

1)it is the "boiler" relief valve, and yes I realize I should not have a 120 psi on there.

2)It is not a new install, over 3 years, so while I never really paid attention to the psi previously, I figure it was not at 58 psi before the relief valve blew. I had the thought of a bad pressure regulator, but I didn't see anything in the manual that said one was built in. Error message says check water pressure sensor, though I question if that is the culprit or just a symptom of the high pressure in the system.

3)Definitely possible the heat went on, thanks to a thermostat left at 65 ish while the AC was cranked up so a bad expansion tank is a good lead.

Really appreciate the responses.

bwdh20

As an extension of the above, as per the safety issue, the machine shut's itself down with the high pressure. so the unit is not currently running.

gennady

1.Test heat exchanger for DHW
2. Test automatic feeder
3. Test expansion tank.
4. Leave 30 psi safety valve in place.

bwdh20

Welp, i replaced the expansion tank and water pressure sensor, and still the problem exists.

By isolating the water lines I've come to realize the pressure shoots up when the DHW cold water inlet is opened. So could the problem be the flow sensor? Or is it(as has been mentioned) the dhw heat exchanger?.

I'll be talking to Navien again tomorrow, so I figure I'll track it down then, but the exchanges here have helped me gain an understanding of the unit, so again, all responses are much appreciated.

njtommy

Sounds like it's time for a new heat exchanger.

bwdh20

Difficult install?

Rich_49

Maybe the diverting valve which switches the unit from Space heating to DHW is settled in a bad place . These valves have been suspect or downright malfunctioned before .

JStar

But the diverter valve is completely on the boiler side.

Rich_49

New Plate HX and follow the recommendation for =<40 psi on the domestic side .

bwdh20

Ya cracked plate in the heat exchange was the diagnosis, part on it's way. install tomorrow.

How do I limit psi for domestic side?

Rich_49

https://search.yahoo.com/yhs/search?p=whole+house+pressure+reducing+valve&ei=UTF-8&hspart=mozilla&hsimp=yhs-004

Xmytruck

Which heat exchanger failed primary secondary or hot water? Why do you need a pressure reducing valve out of curiosity? I'm surprising The company did not replace the unit. Did the company state you have too much pressure on the domestic side ?

jonny88

Hate to be a hater but not a Navien fan.But they do have good support and I guess for a boiler that costs about $400 to make they can well afford to replace parts.Send a pic of install.

Rich_49

They do have plenty of practice in the support and warranty departments . Not to mention the very experienced recall department since more than 100,000 units have been recalled since introduction in the US . 2013 ,13,000 units due to carbon monoxide issue .

jonny88

Wow Rich I didn't realize they were that bad hence the constant changes to their unit.What an incredible marketing team though and have definitly shaken up the market.Feel bad for the consumer though.

Xmytruck

The funny thing is that plumbers still install them and recommend them. I am on my second unit and have no confidence. my hot water pressure value went off two weeks ago and my installer told me nothing is wrong and to keep eye on it. All I hear about the unit is that there great and millions are installed without issues. I personally have had nothing but issues (crack HX, manifold leaks, etc)with the brand I will never use them again. when I got the unit installed three local companies highly recommend navien only one recommend WM97. Wish I went the wm97.

Snowmelt

Manifold? they dont come with there own manifold. they do have an aftermarket manifold but it made from watts

jonny88

Unfortunately to many people come here after the fact.Heres the scoop,supply houses (not all)are interested only in sales.Of course there should be no issues in the first couple of years but after that try and get your installer back.A lot of people call it s throw away it but that's the competition.I have 3 supply houses in a 5 mile radius and this is their number 1 seller..Easy install etc and unfortunatly the homeowner is at their mercy.On a daily basis guys in the field see some crazy stuff that is why some threads here get heated as the good guys are frustrated and competing against low lifes

njtommy

I have a Navien Ncb combi in my house. It's been in now for a year and I really like it a lot. I guess only time will tell. It does seem like they have come a long way.

Xmytruck

John the way your reply reads is that the majority of plumbers are lowlifes. If navian is the best seller in your area or why are people installing them. My only conclusion is that plumbers know the issues and they know they're going to cash in. The plumber who installed mine is a good guy and been my plumber for six years and he scratches his head every time he comes to my house.


Tommy
Have had mine installed since Feb and I have gotten two e515 error codes. The quick install manifold start leaking and my hot water pressure value leaked two weeks ago. My plumbers response to the error codes the new systems are computers and they need to be reset once in a while. His reponse to hot water pressure value was "most plumbers would just open the valve and hit with their pilers and if leaks again to call". I have zero confidence in the unit and in my installer.

jonny88

Ask Gennady what his thoughts are on the unit.You won't get better info

njtommy

Knock on wood I've not had a single problem. I work as a Commercial hvacr service tech. I installed my unit after reading the the installation manual several times. I also have water treatment in my boiler and for domestic water I have a well that gets filtered and treated.
I also did combustion test and confirmed has pressures. Every thing was in spec as per there directions.

bwdh20

Install complete. Bit of a pain, but not terrible. Unfortuneately still no freaking how water, (it did fire up the boiler side) call Navien they say it's either x or y(I kind of forget, three way valve or some circuitry) and I need a multimeter to test one of the two( the circuitry thing).

Got the multi meter and about to call back. Getting a bit peeved. If I need more parts I won't see hot water till Monday at best.

bwdh20

New issue is the flow sensor. Works intermittently. I do wonder if it was jostled during installation of heat exchanger. And I am still hoping the issue clears up the more it is used.

I must say the technical service has been very helpful and they send parts without much question.

But the machine, which had not been a problem before, has been a major pain this past week.

j a_2

The mod cons are here to stay, who knows maybe even someday they will be required, as opposed to cast iron..Imay have missed the post but how was this unit sized, Can u find in the program how many times this unit has cycled..Sounds like to me unles you get this under control, you may be in for a long cold winter...If I were I would insist on a new unit..They may be willing to swap it out, provided it was installed to specs
by a qualified installer, with permit..I hope it was

jonny88

Come on @ j a permits, qualified installer ,sizing ,you know better than that.Buy unit ask for advice from counter guy and away you go.(tongue in cheek and not aimed at poster of thread).You can always call a service rep they will come and help you out.Iron out the kinks now before winter comes you dont want to address than on a below freezing night.Take some pics of install plz and whats your location they usually have field guys out there who will do repair and Navienpicks up bill.
Good luck with it.

j a_2

Correct, shame on me...lol...happy Friday...You to Rich...happy Friday.. And thank you..Seriously..

bwdh20

The unit was installed by a licensed plumber. I assume it was sized right, I've never had problems with lack of heat or hotwater in 3.5 years of use. 2000 sq' of heating and 2 showers. No washing machine no dishwasher. So I kind of doubt the thing is undersized.

Would overuse make the heat plate crack?

bwdh20

As far as ironing out kinks. Yeah I'm glad this happened in august.

Really really hoping the flow sensor is the last issue.

Looking at the 30 yr old Wells McClain combo boiler/dhw sitting next to it(2 family house) with much more appreciation. Yeah it's bigger and it's prob not as efficient(though my heating bill is pretty darn low) but I've had no issues with that in 14ish years of use.

Snowmelt

bwd, you said your unit was installed by a license plumber, plumbers are not technicians. one of the only things plumbers are qualified for is venting of waist pipe. in reality accept for the back flow, which now I can do with my hvac license a master plumber is not a license boiler installer

jonny88

Snowmelt thankgod I am qualified to vent waste pipe now I have to find someone qualified to install it...

RobG

jonny88 said:

Snowmelt thankgod I am qualified to vent waste pipe now I have to find someone qualified to install it...

@jonny88, at least you can spell "waist pipe" correctly and use proper grammar!

jonny88

Honestly Rob I couldn't give a crap about grammar or spelling.Some of the finest mechanics I have worked with have little schooling partly because trade school was done away with a long time ago.I do take offense when a HVAC guy is way of base with a statement like that.Of course a Lic Plumber has to school himself on hydronics etc and for the most part a lot of us do or else we have the sense to call in a designer and work in tandem like Rich etc.But remember you need a Lic to run gas pipe so if you don't have it the plumber who is covering your **** in my opinion should be reported unless he is doing the gas work himself.Its a topic that has been discussed extensively here so please refrain from stupid statements saying we are unqualified.There is truth to the statement but again there are many threads related to this topic so lets not bring it up again.Remember without a Lic you should not touch gas pipe.

j a_2

Me being just a dumb plumber is trying to figure out if someone here is posting nonsense about licenced plumbers...That's just plain wrong..But I have been known to post before thinking...Remember I am just a plumber

Rich_49

Snowmelt ,

I actually know you and you I . What you have stated is so far off base I am astounded , and that's hard to do . By the way , you cannot do a backflow certification , that is a whole different license . By the way , it takes 10,400 hours of field experience and 4 years of 2 nights a week at school to even be permitted to take a master plumbers test in NJ . less than 20% pass . 2% of that 10% is real plumbers . I could go pay a fee and take your hvac test tomorrow and pass . That license is more of a joke than the contractors license which anyone can get by paying their 90.00 . Georgie , I am surprised to hear that out of your mouth , I forgot more than you know , hate to be cliche but it's so . Keep on installing the Naviens and hope you don't get caught up in one of the recalls . Just so ya know . Whenever NJ or any state makes licensing mandatory , it's usually because they need money . Once you're licensed is when the real fun begins . Wait till the CE that is required . See you in class , I'll be the guy standing in the front .