Adding Basement Radiator Zone

DJDrew

Hello All,

Working from home due to COVID-19 (in my basement!) during the cold months has inspired me to add some panel radiators to stay warm. Upstairs are all cast iron radiators that are oversized connected to large cast iron pipes, because of this the system never asks for more than 140 degree water, even on the cold days, and there is an ESBE on the boiler set at 131.

Using a heat loss calculator, I have calculated the basement area to need 12-15k BTUs. I selected two identical panel radiators that claim to put out ~6200 BTUs each @ 140 degree water temperature.

A few questions as I pipe this in....

1. Any thoughts or suggestions on piping this in? Should I pipe this in to the existing cast iron main supply/return mains that run around the perimeter? Or would I be better to run the rads on their own supply/return piping back to the boiler and leave the upstairs piping alone? Either is fairly feasible, one just involves more copper.

2. If I run the these two panel radiators panels on a dedicated run back to the boiler, I could tie them in so everything is one giant zone or I could potentially zone the basement at the risk of short cycling the boiler. Perhaps I could add a garage heater to 'add mass' if zoning makes sense.

Any thoughts or suggestions? Thank you!!

Ironman

Since water takes the path of least resistance, you’ll need to create another zone with its own circulator, thermostat and pump control.

What type of boiler do you have? Cast iron or mod/con?

EBEBRATT-Ed

On it's own zone. Anything else will be nothing but trouble.

DJDrew

Thanks for the suggestions so far. If I pipe the basement on it's own dedicated supply/return back to the boiler, that leaves the options open in the future for controls. I'd probably prefer to stick with a single circulator and use zone valves, as the ESBE protection loop with multiple circulators starts to get more complex and I prefer simple.

Making it's own zone will probably short cycle the boiler, it is a cast iron Slant/Fin SE105. Is there anything I can do now to help plan for this likely issue?

Ironman

You should be ok with a cast iron boiler, there's usually enough mass there to prevent short cycling.

hot_rod

what size boiler, you could calculate run time with that size load.

DJDrew

Thank you, I ordered and picked up the last few parts to handle piping and basic zoning. I'll check back in soon.

I may also pick up a hydronic fan heater or radiator panel for the garage as well, since it would be a simple tie in at this point with all the other piping. It'd be nice if the garage isn't 50 degrees when I am working at my workbench.

DJDrew

hot_rod said:

what size boiler, you could calculate run time with that size load.

@hot_rod it is a 105,000 BTU boiler. https://www.slantfin.com/products/sentinel-residential-gas-boiler/

DJDrew

All, as an update, the new panel radiators are mounted, piped and zoned. I have been noting the run times and below are my observations. (Sorry for the lengthy update.)

At first the boiler would run for 3 minutes before hitting the high limit and then off for about 5-7 minutes. This would repeat for about 45 minutes before satisfying the thermostat. Once the room was at the temp it was much less frequent.

The next day I slowed up the system circulator from speed 3 to speed 2. It then took the boiler run time to ~4 minutes until the high limit was reached. The boiler would then shut off for ~10 minutes. This seems like a step in the right direction. I am still trying to see if the slower circulator speed is negatively impacting the rest of the house with the big cast iron mains and rads

Unfortunately, the aquastat does not allow me to adjust a larger differential than 10 degrees, otherwise I could probably tune the system better for longer idle/run times.

Finally, with success, I found that if I manually open the basement zone valve and disable the basement t-stat, the basement will stay somewhat comfortable when running with the rest of the house. (If the upstairs is set at 70, this means the basement is reading 67-68 (better than the 62 it was with no heat!) We often run a wood burning stove on the main level of the house, so there are days when the boiler only kicks on overnight, so I think it is worth keeping the zoning so the basement has heat on those days.

Would it be strange to put a toggle switch in the basement that switched control of the basement zone? Position 1 = Zone runs off main thermostat | Position 2 = Zone runs off of basement thermostat. This might reduce cycling when we are not looking for much independent control.

As a side experiment , I tried adding a hydronic fan heater for the garage off this new basement zone since the garage was on the other side of the wall. I have mixed opinions if that is worth keeping, the fan works great only when the hot water is flowing and significantly increases the boiler cycling. However, the heat does not last long once the fan has stopped running in the garage. It almost needs to be something that is on it's own zone that can be run only when I am working in the garage. Perhaps even off the regular hotwater tank.

Would a smart pump like the Alpha2 provide much benefit to auto adjust when the different zones are running?

Also, would the only other way to lower cycling at this point would be to add more panel radiators to the basement zone?