Rinnai Continuum 2424

BradSp

HI Everyone,
I've searched through the archives and I haven't found anything quite like this problem I'm having. We bought a house a couple of months ago. It has an older Rinnai Continuum 2424 tankless water heater. Right from the start we've had problems with it. It gets hot just fine, but then after a couple of minutes it turns to cold. Once you shut it off and turn it back on, then it runs fine again, until it goes cold a few minutes later. Once it turns cold, it never goes back to hot unless you turn the faucet off and then back on.
We've had several people out to look at it and nobody can find a problem with it. It never gives an error code. Until this past weekend. I experimented with it and found that if both covers are on, then it will trip every time the hot water is on. If the top cover is on and the bottom cover is off, it will trip. It gives an error code 10 when this happens. The error code goes away each time you turn the faucet off. However, if the top cover is off or if both covers are off then it runs just perfectly. No errors and it doesn't trip.
It's very frustrating when you know you have a problem and then the techs come out and can't find anything (much like when your car is acting up). I can only assume that the techs take the panels off and then do the testing, which would explain why an error code never came up.
I've attached a couple of pictures showing the units. Is there something missing that might be causing the problem? I just don't understand why it runs great if the covers are not on it, but if the top cover is on then it trips every single time.

Any help would be appreciated.

rick in Alaska

Check online for Rinnai error codes and you will find it is most likely an intake or exhaust issue. Possibly something plugged either in the main exhaust terminal or in the unit itself. Might be time to clean out all the dead bugs.
It also says it could be a gas pressure problem, which would be something else to look at.
Rick

rick in Alaska

Try this:
https://www.rinnai.us/documentation/downloads/Troubleshooting_Tankless_Water_Heaters.pdf
Rick

Firecontrol933

I would suggest that you find someone that sells, installs and maintains these units to come and take a look. I'm thinking the other people you had look at it aren't familiar with what it takes to troubleshoot and maintain it.

Besides, being a new home for you, now is the best time to learn what equipment you have and what to expect from it and the maintenance suggested by people that know it.

BradSp

Ok, I do appreciate it. I'll give looking at the exhaust a try. I'm fairly handy around the house, but I'm not sure if I want to dig too deep into the system. Most likely would just get myself in over my head.
I just don't understand if the cover exhaust opening is clear, how putting it back on could cause it to trip. If there was blockage, wouldn't it trip whether the cover was on or not? Also, I don't believe it has a valve to use to flush the lines. Unless I have to cut the lines, I'm sure I can install that.

Jack

Error code 10 is an air side problem. Haven't touched a 2424 in so long, It could be a sensor. Did the techs pull the inducer motor and clean the fan? Also, once the fan is out get an inspection mirror and look up above it at the diffuser plate on the bottom of the burner tray. Over time depending upon ambient...conditions, it can require cleaning. I think that after 12 years it would be worth ordering a gasket set for the 2424 and when you get it, pull the burner tray and clean the whole thing out. That unit is, I think an '04 manuf.

BradSp

As far as I know, the techs haven't pulled anything out. When they don't get an error code they say nothing is wrong with it and leave. I'm starting to feel like if I want it to work I'll have to do it myself. Is pulling the fan and inducer motor something that a non professional should even try?

BradSp

quick update. I put the cover back on and only attached it with the top two screws and it ran just fine. If I put either one of the bottom two screws in it will trip and malfunction. I'll leave it for now, but there has to be some kind of air intake it's blocking. Very strange.

rick in Alaska

From what I can tell, and not sure about this, but it looks like it might pull in the combustion air in to the cabinet and not directly to the fan with a sealed pipe. Can you get us a picture of the exhaust system?
I am strongly thinking you have a blockage in the air intake area, especially with the info you have given us. See where the air enters the cabinet and check for a blockage.
Rick

BradSp

There's nothing coming out of the top of the unit. Just the exhaust that comes out of the top front side of the cover. I did crawl under the house to get a picture of the piping going to it. By no means is it a great picture. I had a knee replacement about 5 months ago and you wouldn't believe how painful it is to crawl on my knees. I was shaking pretty bad when I took it. Do you think that pipe to the left would be the air intake? If so, why on earth would they put it under the house?

rick in Alaska

Lets see a picture of the whole unit from a distance so we can see all of it at once, and also a picture of the cover.
Rick

BradSp

Here's the whole unit. I know the bottom cover for the pipes needs to be redone. Haven't gotten to it yet with everything else I have to do with the new house. Sorry about the sideways view on the second pic. I can rotate it, but it won't stay that way when I save it.

rick in Alaska

The combustion air is coming in from the front cover through the lower slots, so if those holes are clean, you should be getting good combustion air in to the unit. If they are clean all the way through, then it is time to take it apart and make sure the insides are clean. Probably need to do it anyway, just because it is time. I just took one apart yesterday that was vibrating and found a few dead moths in the fan assembly. Doesn't take much to get it out of balance.
Rick

BradSp

Ok, so I need to take the fan apart?

rick in Alaska

I would start there unless the inlet holes on the cover are blocked.
Rick