Jac04
Member
I'm new to the forum. After lurking around a little and finding a tremendous amount of good information, I decided to join.
Recently, a Navien CH-180 ASME modulating condensing combination boiler was installed to replace my original oil-fired boiler. I’m looking for feedback and advice on setting the boiler up for efficient operation. The installer is not educated regarding this – they simply set the supply temp to 160 F and walked away, which is unfortunate, so I’m on my own. After some quick research, I immediately set the supply down to 140 F, but now I have become more educated and want to take full advantage of the new boiler.
Location:
Just outside Windsor Locks, CT
House: 1994 built raised ranch.
1st floor = 750 square feet
2nd floor = 1350 square feet
Heat Zones:
Zone 1 = 1600 sq ft of heated space (1350 upstairs and a 250 mudroom/entry downstairs). 80 feet of baseboard (finned length).
Zone 2 = 500 sq ft. 7 feet of baseboard with a Myson Whispa III 9000 wall-mount.
Right now I have the optional Outdoor Temperature Sensor installed and I have the Supply Temperature K-Factor set to 1.4. (Navien calls their outdoor reset a K-Factor for some reason.) To simplify things, I am not using Zone 2 right now. My burn times range from about 12-18 minutes, with about 9 minutes in between. I have nice even heat without any temperature swings (as a matter of fact, the reading on my thermostat never varies from the t-stat set point during steady-state operation). During the burns, the boiler modulates down, always stays firing (no short cycling), and the supply temperature seems to track slightly below the K-Factor curve as specified by Navien.
What’s interesting to me is that the boiler does not seem to be producing any appreciable amount of condensate over the last few days. I put the drain hose into a 5-gallon bucket when I started running on the outdoor reset a few days ago, but it has only produced about ¼ cup of condensate in that time. Daytime temps have been in the very low 30s with nighttime temps in the mid teens. Surely I’m loosing condensate to evaporation out of the bucket, but I guess I was expecting to see more condensate.
For reference, K=1.4 curve has outdoor temp and supply temp roughly as follows:
50 F = 104 F
41 F = 113 F
32 F = 126 F
23 F = 135 F
14 F = 145 F
5 F = 155 F
Here are my questions and topics for discussion:
1) Should I try to lower the K-Factor even more?
2) Is there any benefit to trying to achieve even longer burn times by lowering supply temperature even more?
3) Are there adjustments that should be made to my Honeywell programmable thermostat? Right now, the cycle rate is set to 3. I’m not sure exactly what this does. However, would lowering this to 1 give me more ‘lag’ – resulting in longer burn times as well as longer off times? Would this be beneficial?
4) Why would I not be getting more condensate? Is it just that I am at the high side of return temps, and I need even lower return temp to condense more.
Now, I also need to start thinking about what I’m going to do with Zone 2, which is my downstairs room on a concrete slab. It is 1 bathroom and a kid’s play room. Baseboard is installed in the bathroom. The Myson Whispa III 9000 was installed in the main room due to ease of installation. It has a fan that comes on when supply temp hits 110 F. So, when the supply was set at 140 F, the fan would always come on when Zone 2 called for heat, and the room would heat up nicely. Now that I’m operating on outdoor reset, if Zone 2 calls for heat when its 41 F outside, chances are the supply temp won’t be hot enough to kick the fan on and I’ll have the equivalent of about 1 foot of baseboard (if I’m lucky). Any suggestions? Due to the layout of the room & being on a slab, I’ve been told by several people that installing baseboards would be very labor-intensive ( = $$$).
Thanks in advance for any help & guidance – it is much appreciated.
-Jeff
Recently, a Navien CH-180 ASME modulating condensing combination boiler was installed to replace my original oil-fired boiler. I’m looking for feedback and advice on setting the boiler up for efficient operation. The installer is not educated regarding this – they simply set the supply temp to 160 F and walked away, which is unfortunate, so I’m on my own. After some quick research, I immediately set the supply down to 140 F, but now I have become more educated and want to take full advantage of the new boiler.
Location:
Just outside Windsor Locks, CT
House: 1994 built raised ranch.
1st floor = 750 square feet
2nd floor = 1350 square feet
Heat Zones:
Zone 1 = 1600 sq ft of heated space (1350 upstairs and a 250 mudroom/entry downstairs). 80 feet of baseboard (finned length).
Zone 2 = 500 sq ft. 7 feet of baseboard with a Myson Whispa III 9000 wall-mount.
Right now I have the optional Outdoor Temperature Sensor installed and I have the Supply Temperature K-Factor set to 1.4. (Navien calls their outdoor reset a K-Factor for some reason.) To simplify things, I am not using Zone 2 right now. My burn times range from about 12-18 minutes, with about 9 minutes in between. I have nice even heat without any temperature swings (as a matter of fact, the reading on my thermostat never varies from the t-stat set point during steady-state operation). During the burns, the boiler modulates down, always stays firing (no short cycling), and the supply temperature seems to track slightly below the K-Factor curve as specified by Navien.
What’s interesting to me is that the boiler does not seem to be producing any appreciable amount of condensate over the last few days. I put the drain hose into a 5-gallon bucket when I started running on the outdoor reset a few days ago, but it has only produced about ¼ cup of condensate in that time. Daytime temps have been in the very low 30s with nighttime temps in the mid teens. Surely I’m loosing condensate to evaporation out of the bucket, but I guess I was expecting to see more condensate.
For reference, K=1.4 curve has outdoor temp and supply temp roughly as follows:
50 F = 104 F
41 F = 113 F
32 F = 126 F
23 F = 135 F
14 F = 145 F
5 F = 155 F
Here are my questions and topics for discussion:
1) Should I try to lower the K-Factor even more?
2) Is there any benefit to trying to achieve even longer burn times by lowering supply temperature even more?
3) Are there adjustments that should be made to my Honeywell programmable thermostat? Right now, the cycle rate is set to 3. I’m not sure exactly what this does. However, would lowering this to 1 give me more ‘lag’ – resulting in longer burn times as well as longer off times? Would this be beneficial?
4) Why would I not be getting more condensate? Is it just that I am at the high side of return temps, and I need even lower return temp to condense more.
Now, I also need to start thinking about what I’m going to do with Zone 2, which is my downstairs room on a concrete slab. It is 1 bathroom and a kid’s play room. Baseboard is installed in the bathroom. The Myson Whispa III 9000 was installed in the main room due to ease of installation. It has a fan that comes on when supply temp hits 110 F. So, when the supply was set at 140 F, the fan would always come on when Zone 2 called for heat, and the room would heat up nicely. Now that I’m operating on outdoor reset, if Zone 2 calls for heat when its 41 F outside, chances are the supply temp won’t be hot enough to kick the fan on and I’ll have the equivalent of about 1 foot of baseboard (if I’m lucky). Any suggestions? Due to the layout of the room & being on a slab, I’ve been told by several people that installing baseboards would be very labor-intensive ( = $$$).
Thanks in advance for any help & guidance – it is much appreciated.
-Jeff