Rinnai E75CN Heatting Issues

erinlem77

I have a Rinnail E75CN combo unit. I've had it for 2 years now and it has never worked properly. Sometimes the heat shuts off in the middle of the night and I wake up at 2 in the morning and it's 50 degrees in my house! Then sometimes it's 85 degrees in the middle of the night! It's crazy! No one can figure out what's wrong with this thing. I have no error codes either. Does anyone know what the problem could be? Any advice would be great!

Tom_133

Lots of Pictures, we ned to see what you have for piping. Then you will get plenty of help. Try to get pics from a little ways back so we can see all of it.

Mad Dog_2

Did you install? Contractor? All these great energy-efficient products are very finicky in regards to pipe size supplying them and venting. .....and that missing link....... LACK of ANNUAL MAINTENANCE!!!!!! Mad Dog

erinlem77

Ok Tom will get some pics up tonight! Thanks for all of your responses!

erinlem77

Mad Dog, my father is a licensed pipe fitter and did the piping. We had a licensed contractor oversee the install. I also did some research on my own and while I was reading the manual, I noticed that the PSI should be at 16 to 18 and its reading at a 23 PSI. When I shut the hot water off the water pressure goes to 30. Do you think that has anything to do with the heat not working properly? Thank you!

143friend

I have a Rinnai E75CN combo boiler which is 5 years old. I've performed yearly descaling myself. As of now the heat works, but very little, and although there are no error codes, the temp in my house (while set to 68) is in the low 50's. The radiators are warm but not hot. I have someone coming down on Friday, but it's pretty cold right now. Are there any screens or filter which may need to be cleaned that may be causing this problem? thx for your input.

143friend

Just an update.......my display constantly shows the number 6 (with a temp of 166 showing after that, and the unit says that this means that the zones are calling for heat, but the pump is not operating.

DZoro

Have to find out why the pump isn't operating, pictures of the system would help.
D

143friend

Here's a pic of the unit.

Brewbeer

Step back 5 feet and take another photo, we would like to see all the near boiler piping.

Grallert

erinlem77 said:

I have a Rinnail E75CN combo unit. I've had it for 2 years now and it has never worked properly. Sometimes the heat shuts off in the middle of the night and I wake up at 2 in the morning and it's 50 degrees in my house! Then sometimes it's 85 degrees in the middle of the night! It's crazy! No one can figure out what's wrong with this thing. I have no error codes either. Does anyone know what the problem could be? Any advice would be great!

I'd be interested to know which lights on the display are illuminated. In other words is the hot water (domestic hot water) light illuminated when you find the house at 85? and by chance is the hot water extra hot when you find house cold? Just guessing here but I've had some issues the internal bypass valve getting stuck in the wrong position.
OOOPS I didn't read the date of the original post. Sorry

Alan (California Radiant) Forbes

Usually when there's no error message, the boiler is operating as it's supposed to. If these boilers are operating with the on-board outdoor reset feature, check to make sure the outdoor sensor is reading the outdoor temperature properly. You will have to have an ohm meter and the troubleshooting manual for the boiler which will give you the ohm reading at different temperatures.

It also could be the way the boiler was set up. Check the programming to make sure target water temperatures are realistic for design conditions. You may need to bump up the water temperature.

DZoro

Post a picture of the entire system pumps and piping, we can zoom in if we need
D