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Help with Rinnai M series Code 140

rameye Member Posts: 2
Hi There,

Im new to the board seeking help with a code 140 issue.


I installed this Rinnai MS 60 Boiler 3 years ago in southern new hampshire for the purposes of maintenance heat/freeze protection. The thermostat is usually set to 48. It operates off of propane and has been properly flashed and converted for such. I did the install myself and hired a Rinnai familiar tech to check my work, convert, flash, and set up the unit and check operation. He was very satisfied with the install.

The system is hydro-air with the air handler (basic single speed/no pump) in a first floor closet . I run my boiler temp at 116 in prevent short cycling, I have disabled the outdoor reset feature. It's just under a 60 foot circuit with about 3 foot of lift to the handler which according to the install manual is within spec. The system is configured in line (no close T) so im using the internal boiler circulator to drive the entire system which is an allowable option in accordance with the install instructions.

The system easily makes temp and modulates accordingly, usually operating at 15k btus. During normal heating temps it runs at 25%-35% duty cycle when the temps really take a dive she runs about 50%

I had the unit serviced last year, all looked good. the tech advised me to have the igniters replaced when I hit the 4 year mark. I back flush the unit yearly as the iron content is very high up here. I have a scale cutter in the feed line as well as a magna flow unit inline with the heating circuit that was highly recommended.

The Issue-

Last year at the end of the season I was at the the house and notice the boiler was not running it showed a code 140. I backflushed the boiler itself and the circuit and got some crud. Reset code, checked operation all good. Checked it again at the beginning of the heating season (its off during the warmer months, no DHW circuit) checked for crud, none found, fired up, normal operations.

Boiler service tech did the annual and gave it the thumbs up.

This year we started off with some cold temps where it had to work a bit and we just had a week with well above normal temps so basically no operation of the unit ( I have an thermostat app and check it). Temps started to dive again this we week , the house notified me temps were dropping below set point (via home monitor). My neighbor went over and saw it put up a code 140, and reset the code and this is where I am. Right now I have normal operation but I want this addressed. The house sits on a hill by itself and the snow pack is pretty tall so getting access is not so easy.

I'm contacting my boiler guy today, but at same time Im looking for some possible causes. Im afraid he'll come up and check it and see its running fine and do the old head scratch. In my mind it seems like after the system is allowed to rest for a few days or week without use, this happens. Similar to last year at the end of the season...

Where should I/they be looking?? Pressure sensor? Circulator? Something else??

The manuals seem to indicate that the unit energizes the circulator pump and if it doesnt see a pressure increase (im not sure where thats measured) it posts a IP9 fault and tries again (i think) 2 IP9 faults puts up the 140 code and shuts down the boiler.

Thanks for your help


  • psb75
    psb75 Member Posts: 863
    Somebody better be talking to Rinnai Tech support. Preferably your 'boiler service tech' while he is on site. But you could also, since you did the install.
  • rameye
    rameye Member Posts: 2
    Thanks for the advice--Ill let the tech do the talking-- They can route us non techs out pretty fast :)
  • psb75
    psb75 Member Posts: 863
    If you speak knowledgeably and respectfully, they will help you. Study the manual-- especially the part with all of the settings and parameters. Rinnai makes good equipment. And they support it well. Staffing tech support, like everywhere else these days...is not easy. They want to be efficient with their time. A boiler technician in the field who is familiar with the Rinnai products is their preferred 'target' for delivery of technical information.
  • uhmgawa
    uhmgawa Member Posts: 4
    Regrettably my experience is far less positive. The standard level service techs one gets routed to can do little more than read the boiler manual tossed in the factory box. And every so often you get a real doozy with an attitude who seems annoyed he picked up the phone. Although once I recall needing information beyond that of install/maintenance and was transferred to their engineering group. So the assistance is there if you dig for it but I haven't had much luck extracting intelligence from their first level support -- well, beyond what's openly published in a unit's install manual and website service/technical notes.