Hello all, new to the board. There seems to be many very knowledgable heating pros on this board, so I was hoping to get some expert advice on an issue I am dealing with. I will appreciate any input on this matter. I am not very knowledgable when it comes to mod/con boilers, so please forgive my ignorance.
I had a wall mounted Lochinvar Knight WHN155 installed in late August last year, replacing a 79% efficiency Dunkirk cast iron boiler. My system consists of 2 zones of hot water baseboard heat and an indirect Amtrol water heater, which is controlled by a knob on the tank itself . So far the gas savings have been outstanding, but it also has been very mild here. The issue I have been dealing with is the system has had a few lockouts for the ARHL/MRHL, the latest occuring this morning when I woke up and the house was 60 degrees. Apparently the MRHL lockout occurred last night at 8:45 PM and it was in the teens overnight here. I had the installer out twice for this issue, both times they bled it feeling it may be air trapped in the lines. The 2nd time he came out, he spent much time on the phone with Lochinvar support and followed their instructions which was the same as the manual. They asked him to adjust the setpoint of the auto and manual reset limits to 200 and 210 respectively, just as stated in the manual but it would not go over 195 and 200 respectively, so it was kept at that limit. (They admitted there was a typo in their manual). I have had it happen about 5 times now in total, so after reading the manual over and over, the only thing I felt I could do to correct the issue since I was unable to raise the reset high limits was to lower the SH1 and SH2 setpoints to 170 degrees from their 180 degree settings, which I did for about a month and haven't noticed a difference in comfort and haven't had any lockouts since. That being said, last week I experimented and adjusted the setpoints back up to 180, and kept the offset at it's default of 10 degrees, and had the lockout occur again. I understand my baseboard system is meant to run at 180 degrees, so that's why I am experimenting and trying to keep it as close to that number without overshooting the limit. I was thinking of lowering the offsets to 5 degrees or less to try and keep the limit lower. I also understand that the boiler is more efficient if the return water is cooler as well and I don't notice and difference in comfort, so I was wondering if i should just lower the setpoints further. I apologize for the long drawn out first post, but I am trying to explain what I am dealing with in the best manner that I know how.
Thank you for any input, Vinny.