Rinnai RU98i

got2lb

I have a Rinnai RU98i was having problems with it not kicking in and no code, sometimes it would work and sometimes it wouldn't. Replaced the flow servo valve. After replacing the valve the first time I turned the hot water on the unit fired right up and worked fine. I let the hot water run for probably 10 minutes and no issues. Fast forward to 2 hours later and no hot water again and flashing a 41 code. Took the whole thing apart and reinstalled a couple times now. Replaced the thermistors on the outdoor temperature sensors. The heating elements on the lines all heat up and the heaters on the valves all heat up. No idea where to move on from here, and don't want to have to purchase a new unit.

Thanks!

Slimpickins

Has the PCB been replaced recently? If you're getting a code 41 you have the outdoor PCB.

Intplm.

How old is the unit?

What size and type of gas line?

What is the water pressure?

Are there any obstructions…ie. venting, air intake etc.?

Has anything changed that isn't a first thought? (done months ago?)

Are all the dip switches correct?

I have the same brand and size unit as yours and have found these issues on mine and others that could cause this.

Short of calling Rinnai tech support,(they're pretty good), double-check the above issues/settings.

got2lb

PCB has not recently been replaced.

Unit is roughly 13 years old functioning perfectly the whole time.

1” gas line, 50-60 psi water pressure, no obstructions in venting, haven’t changed any of the dip switches.

Chatted with tech support only thing they said was to call a service company to have them look at it. Never gave me anything to go off of.

got2lb

Is it possible to just unplug the frost protection stuff from the board and have this unit work? It’s in my basement. I didn’t realize it even had it on it.

Alan (California Radiant) Forbes

https://forum.heatinghelp.com/discussion/comment/1802384#Comment_1802384

Tech. support prefers to work with someone familiar with boilers for many reasons. Do you have a regular service person? Where abouts do you live?

got2lb

Closest service to me is 90 minutes away. Thats who they told me anyway

EdTheHeaterMan

Probably not an option to remove the frost protection from the PC board. I would need to know what software was controlling that board to know if there is a way to disable that feature. You may get a few more years from that appliance but is it worth the cost of the repair?

Maybe a new one that has a more local service company is a good idea.

Are you in such a remote location that all water heater professionals are that far away? Perhaps you can install it yourself, that saves on the cost of a new one. but when it gets to be 13 years old in 2036, you might be able to get a local guy.

Intplm.

https://forum.heatinghelp.com/discussion/comment/1802384#Comment_1802384

That's a shame. But sometimes tech support will only talk to the installer. In reading your response, I would double-check the dip switch settings. Annoying I know, but what do you have to lose? And while you are at it, make plans to have the installer call tech support when you have them back at that unit.

got2lb

There's local plumbing shops in the area none that sell this brand. My brother in law is a plumber hvac guy he's the one who installed it and has been trouble shooting it. The one Rinnai recommended is the closest one to us who actually services this brand. I have noticed parts are not easy to come by, not sure if it's just this model or that's a rinnai thing as a whole or what?

I will definitely go through and double check all the dip switches just to make sure nothing got bumped. I'm already considering a new model before I hire someone from 90 minutes away to come look at this unit because I'll probably have almost half the cost of a new one in it for them to come.

What's a good brand to go with for longevity and parts availability?

WMno57

@got2lb asked: What's a good brand to go with for longevity and parts availability?

Not so much Brand, but type of boiler. For longevity and parts availability a simple lower efficiency cast iron boiler beats any mod con or combi.

Companies come and go. Brands come and go. Cast iron boilers have fewer proprietary parts, and worse case, if a proprietary control board for an orphan cast iron boiler is not available 25 years from now, it could be made to work with off the shelf parts. Much harder to do that with a mod-con. Of course the mod-con isn't going to last 25 years any way.