Converting to low temp rads and home run distribution with Energy Kinetics boiler?

HomeownerDustin

I'm looking at getting an Energy Kinetics system to replace our 45 yr old gas boiler and DHW tank. We currently have old convectors that require 180 degree temps on a monoflow distribution system.

Question: can we, in the future, convert the heat emitters to low temp rads and re-pipe everything to a home run distribution system if we got an EK boiler now to work with our current distribution system? Is this crazy and/or crazy expensive?

Rationale: I have a 2 family. If/when we take over both units, I'd like to put in new low temp rads all over and do home runs to a single, large manifold to run off a single boiler. My unit's (1000 sq ft) heat loss averages 35k BTU in the cold months. My tenant's units (1200 sq ft) heat loss is about 45k BTU. Each of our current boilers are rated at 100k BTU. I think a 100k BTU EK system with indirect boiler would suffice for everything.

Finally, my "pie in the sky" option is doing an air-to-water heat pump with low temp rads. I'm also getting quotes for solar right now. So if that is feasible, I may just do a small boiler replacement as backup when the old oversized one breaks.

Steamhead

Have you done a heat-loss calculation on the building?

Hot_water_fan

can we, in the future, convert the heat emitters to low temp rads and re-pipe everything to a home run distribution system if we got an EK boiler now to work with our current distribution system?

Yes. If you haven't already, look at the Caleffi Idronics journals, which cover exactly this.

I second @Steamhead, you need a good heat loss before anything. 80kBtu for a home that size is pretty extreme. How much gas did the two units use last year?

heatdoc1

If you contact Energy Kinetics they can help you with the boiler sizing and answer your distribution questions as well

brnrman1

Thank you for your question, @ HomeownerDustin .
Piping both units off of a single boiler with the loads that you mention should not be a problem. There may be site specific reasons why this could be easy or difficult. We would recommend primary/secondary piping on both monoflow loops to ensure even heating through your radiation. There will not be a payback vs the cost of lower temperature radiation.
Air to water heat pumps are not yet common, and future versions may be able to service higher hydronic temperatures. Currently, keeping a gas boiler as “backup” or for cold months for any heat pump would be a wise choice. Boilers can also run with very low power consumption in case grid stability or power outages are a consideration. There may be a good payback if you are adding solar for your electrical needs.
Please contact us or PM me if we can help further.

HomeownerDustin

Steamhead said:

Have you done a heat-loss calculation on the building?

I did this empirical heat loss estimation with this method over a handful of the coldest months: https://www.greenbuildingadvisor.com/article/replacing-a-furnace-or-boiler it was between 32-35k for my u it. I also did a slant fin calc and came to a similar number. 

I guessed my tenants heat loss based on a bill that i saw compared to mine. We’ll be getting more insulation in the home through the state. 

HomeownerDustin

Hot_water_fan said:

80kBtu for a home that size is pretty extreme. How much gas did the two units use last year?

Do you mean it seems like excessive heat loss or not enough heat loss for 2200 sq ft? I'm assuming it sounds high.