Is my boiler operating properly or is it defective/undersized?

[Jean-Sebastien Stoezel]

Did you happen to program your thermostat heat cycle rate to 3?

Thank you for the reply. When going through the user manual here: http://www.completeheating.ca/images/pdf/RTH6400D.pdf
I am not sure I am finding an equivalent setting than you are referring to.

 

[Fitter30]

Thank you for the reply. When going through the user manual here: http://www.completeheating.ca/images/pdf/RTH6400D.pdf
I am not sure I am finding an equivalent setting than you are referring to.

Push fan button and up arrow for temperature same time screen should change in 5 seconds. Function 5 heat cycle rate set to 3. Heres the install manual couldn't get your site to pull up.
https://www.manualslib.com/download/802727/Honeywell-Rth6400-Series.html

 

[Sponsor]

 

[Jean-Sebastien Stoezel]

Push fan button and up arrow for temperature same time screen should change in 5 seconds. Function 5 heat cycle rate set to 3. Heres the install manual couldn't get your site to pull up.
https://www.manualslib.com/download/802727/Honeywell-Rth6400-Series.html

Thank you for pointing me to this manual. This is what I had in the thermostat
Function 1: 2 (heat only), which I believe is correct.
Function 5: 1 (gas/oil steam or gravity system), changed to 3 (hot water or high-efficiency furnace).
Function 13: 1 (smart response technology on).

 

[Jean-Sebastien Stoezel]

Thank you for pointing me to this manual. This is what I had in the thermostat
Function 1: 2 (heat only), which I believe is correct.
Function 5: 1 (gas/oil steam or gravity system), changed to 3 (hot water or high-efficiency furnace).
Function 13: 1 (smart response technology on).

With these modifications, I can see a different behavior. The boiler seems to be activated more often, for shorter runs, i.e. 10min on, 10min off and so on. I am guessing this is to maintain minimum temperature in the system.
The issue I am observing with this is that in 10 minutes the water does not have the time to fully circulate thorough the entire house. This is more visible on some of the circuits, particularly the upper floors and far away from the boiler. I do not have an off delay on the circulator. I had asked the plumbing company to install one since I had hardwired the circulator to run 24/7, and this seemed to help keeping consistent water thorough the system (and help with cold starts). The plumbing company deemed this was not necessary.

With the shorter, more frequent cycles, it looks like I would need to have an off delay on the circulator. How energy efficient is it to run these more frequent shorter cycles?

 

[Dana]

Thanks for the reply. The heat loss study from 2 different plumbing companies suggested that the house needed a net 100kBTU boiler. And so, when the old 210kBTU boiler died, the first boiler that was installed was in fact a CGI-5 with a rating of 119kBTU . This boiler could not maintain heat in the house and the CGI-6 was installed.

When the heat loss calculations were that far off the culprit is usually excessive air infiltration, much of which can be fixed with a round of blower-door and infra-red imaging directed air sealing (which would also find any gaps in the insulation.) If no contractors in your area provide that sort of service, a diligent DIY-er can figure out and fix the worst offending leaks using a USD $200 FLIR One and a large reversible window fan.

This house is a lumber frame with what appears to be 4" worth of saw dust in the walls, and pretty well packed up to the ceiling of each room. Most windows are now recent (less than 10 years) PVC type, double or triple pane with Argon. They are some original windows that are single pane with storm windows fitted. The basement was recently renovated with spray foam bringing the insulation to be over be code requirements. Some rooms in the house have been renovated, the studs have been extended to bring the walls to 6" deep, with R24 insulation.

Hopefully the foam extended from the basement slab up and over the top of the foundation & mudsill all the way to the subfloor above. The foundation sill and band joist are usually responsible for more air leakage than all window & door leakage combined, even with the "before upgrades" versions of your windows.

Sawdust insulation is good for about R2 per inch if it's in a very tight stud bay, but it isn't very air retardent on it's own (unlike it's cousin, cellulose insulation.) Air leakage into the cavities on either the exterior sheathing/siding side or the interior side will allow parasitic convection loops to undercut it's performance.

While I understand that the house is not energy efficient, the return temperature should be able to be much more than what I am observing. Particularly these days when I am testing the system, running extended boiler runs (close to 90min), and in unusually warm weather conditions for this time of year. We have been sitting at -5C - today is actually -1C. This is a far cry from the -20C to -30C we should be going through right now.

I can never reach that 60C water temp return particularly if the bypass is closed. To reach this temp I need to both fully open the bypass and partially close the supply isolation valve.

To protect the boiler, fully open the bypass- you won't be losing any efficiency with it open. It's fine to let the boiler run hotter than the radiation, especially now that the basement has been air sealed and insulated.

Measured on the radiation side of the bypass loop, what are the supply and return temperatures going to/from the radiation? (This is easy to measure with an infra-red thermometer directly on the pipes, if they're black iron. If they're galvanized, copper or brass put a spot of spray paint (any non-metallic color) or a wrap of hockey tape on the pipe where you're measuring the temp to provide a higher IR emissivity.)

 

[Dana]

Interesting reading. So i assume that my Triangle Tube Prestige Solo 110 is a condensing boiler,and the Weil-Mclain CGI-Gold seies 2 is not a condensing boiler.
I can assume that is why one can handle lower return water temperatures, while the other one requires a minimum of 130F

That's correct.

 

[Nebojsa]

Thanks for the reply Dana. It all makes sense now.