I'm feeling lost

stufine

Hi everyone.

I hate to ask for help, but I have gotten myself lost.



I recently bought (land contract) 2, 9-family buildings near cincinnati, ohio and have been trying to figure out which way to go to try and save money and to be ready for the future. Right now the heating bills for the building are $1k in Dec & Jan. The past peaks have been near $2k in the same months. I'm trying to get on the correct path for when this boiler craps out.



Boiler: Bryant cast iron from early 70s. 425k output (nice to see a temp gage showing 350f+ going up the 10" flue)



Sits in center of building. 2" copper off the unit T's to 1 1/2" copper that runs to ends of building and drops to 1 1/4 across floor, it then drops to 1" going up the the units. t's off the 1" to 3/4 baseboard in the units and returns to boiler same size as supply. Each 2 units makes a loop into the main 1 1/2 runs. Total of 4 loops.





This building is all brick, no insulation and has new windows with about 600sf per unit. Each unit has 2 doors and 5 windows. A rough calc heat loss on end units put it close to 40k. (less on center units) On a typical day I figure the units are getting just over 20k in heat. This would be why my end units are about 6f+ colder than the center units.



I don't have any room left to add more baseboard in the rooms.



I also need another water Heater soon. So now I'm trying to think ahead for what I should plan.



I thought about installing zone valves on the center units to lower the temps (75+ on cold days). It wont help with heat to the end units unless I turn up the boiler which in turn wont save any money. This boiler does use an outdoor reset.



Thinking of a new boiler with an indirect. If I add zone valves I need to cut and connect the baseboard since they supply from 1" copper with 1/2 unit fed to right and other 1/2 left.(3/4 fin) If what I understand I wont be using a condensing boiler? I normally have been pushing 140f water.



If I'm going to be doing remodel/replacement, Do I think about using a manifold to feed each apartment ?

Zone valves or the smaller pumps (pricing about the same?) each unit has about 60-65' of 3/4" fin tube.





The more I read, the more I'm losing myself.

SWEI

start by balancing the radiation

in those end units.  You could swap out the baseboard for high output base or low profile panel radiators.



Who pays for the heat?  Any tenant control over heat now?



Insulation under floors and in attic?  Any chance of furring out walls on either side to add some?

stufine

I do

pay the heat.

Tenant has no control over heat.

I did install 1 1/4 ball valves in 3 of the loops when I replaced 1 unit fin tube with new ones with the hope of balancing the center units.

The cost of the higher BTU baseboards aren't making my plans easy. I wouldn't say this is low income but I'm trying to keep from increasing rents.

I have considered 1 Toe Kick setup for the end units lvrm/dnrm (3 outside walls) since the bedroom if fine.



I have thought about furring the outside walls which is another reason I installed the ball valves. It would also allow me to install 12' carpet instead of 15' if I went with 2x4 walls.



This year I do plan to try and blow insulation in the roof area. It's a flat roof and space is limited up there. 12" at the bottom, 30" at top. Basement area stays about 60f



The other 9 unit building has an even older gravity boiler. a 1940's bryant with 3" welded supply/returns with cast iron rads. That one is cheaper to run. $700 compared to $1k. I'll keep the rads with whatever setup once I figure which way to go.

SWEI

increasing comfort while reducing fuel use

is entirely do-able using outdoor reset control, but a fan coil (toe kick) may not blend well with baseboard.  Matching the radiation to the heat loss in each space will allow you to keep all the units comfortable while keeping overheated tenants from opening windows to manage their comfort.  I'd start there before I changed anything else.  If the future attic insulation covers all of the spaces, it will allow you to install a smaller high efficiency boiler which will run at reduced operating temperatures and save a LOT of fuel.

stufine

I use outdoor reset

and since I live nearby, I will adjust it lower if the week calls for decent weather. Some of the copper lines are starting to show pitting. That's why I'm looking towards the future todo.

SWEI

pitting

on the inside?  What are your velocities like?  What about your water pH?

stufine

not sure

that hasn't been tested. The only thing the owners did was vacuum the burners and clean the flue since the late 70's.



The pits are starting to grow green on some of the heating pipes (1 1/2) in certain areas on the outside. I just recently replaced some of the potable copper when those pits started leaking.



maybe pits is the wrong word to use?

SWEI

pitting

sounds like it might be coming from the inside.  Time to cut out a section of pipe for analysis.

stufine

That's why

I figured I would start looking to replacement in near future. I was looking at switching to a manifold system and making new runs with O2 pex. I read the manifolds would flow 1.4gpm and figured it wouldn't be enough. I guess that's why they split the runs in each unit. Going by that I would end up with 18 circuits? and another for a indirect. Tomorrow I will get more accurate temp drop on supply/return at boiler. ( 60f outside today) If I remember correctly I'm about 10f drop at the units.

SWEI

find out why

the pitting is happening before you start changing parts.

stufine

4hr heating chart (afternoon)

pitting is mostly in laundry area. its in other areas but not as much. had some turns so I'll get back into checking.

here is a chart from live data on the boiler

not much difference between supply and return temps

live data https://cosm.com/feeds/106353

outside temps are a bit off. probe on south side... but it acts like a setback when the sun comes out.

Zman

Condensing

You do not have a condensing boiler yet you are running low temps. You may have to replace the boiler sooner than you think. Your boiler controller should be set so the return temp is always higher than 140.

Your low delta t and pipe erosion is an indicator that you are over pumping.

I think your future plan should be a mod/con boiler, ECM circ, and trvs on the interior radiators. Indirect for hot water.

You should be able to use the actual data from your chart for your coldest day to size your boiler correctly.

Carl