Thanks for the reply MDM!
A few questions:
- Is there a single boiler that serves multiple zones, or are there separate boilers for each zone?
- What are the thermostat settings?
- Boiler(s) run(s) continuously because the temperature doesn't reach the thermostat setting, or boiler heat does switch on/off?
- Gas bill(s) seem(s) reasonable or exorbitant?
- Each of the four units has one boiler. This one boiler serves all zones in the unit. There is a zone valve for each zone, but not individual pumps for each zone.
- I have been experimenting with multiple settings, and usually keep mine in the low 70s. I think the other units keep theirs at the high limit.
- My boiler does not run continuously, and seems to fire appropriately when more heat is called for. The other units... I'm still working on gathering all of those details, but they all worked correctly when we did the home inspection a few months ago.
- I can't currently say, as I've never had a gas bill in this area. I'd think it's on the high end because they're leaving their tstats on, but that's an assumption and a good answer is really relevant here.
All of the boilers are fairly new, but the inspector said "small." Heat at the baseboard is usually above 120, and is extremely hot on the return. I recently raised the water temp of my boiler to over 180 at the aquastat and it gets really warm, very slowly.
I have been trying to learn all I can about boilers and hydronic baseboard, but most of the information I've found isn't answering my questions. I don't know what the water at the baseboard should be, how many linear feet of baseboard for the space I need, how "big" of a boiler I need, or how to really tell that it's fully working at optimum efficiency. There are some YouTube videos that explain some of these parts, so the search continues.
Should I have posted this in DIY? It seemed appropriate for this section since I'm really trying to find a good landlording solution to this. I'm not against paying for an assessment, but I'd really rather learn it for myself and try to fix it for myself.