Safe to cap steam boiler?

BronxMatt

I’ve got a big old boiler that provides steam heat to the radiators, and also provides heat to a separate hot water tank via a coil. I’m in the process of replacing the heating with an all electric system, so i won’t need the steam heat and will be removing the radiators and the thermostat, but for now i will continue to use this boiler to heat the hot water tank. 

My question is if it’s safe to cut and cap the steam pipe where it exits the boiler, or if this would be dangerous in case steam builds up and has nowhere to go. The thermostat will be removed so there won’t be any call for heat, but i have no idea if steam builds up when the boiler runs to heat the coil for the separate water tank. 

Mad Dog_2

Hold on there.   Can you send a picture of what pipe you want to cap? Thanks  Mad Dog 🐕 

Steamhead

@BronxMatt , you say you're going all-electric?

In the Bronx?

Using heat pumps?

Better keep the steam for when it gets really cold. Otherwise Con Ed or whoever will eat your bank account for breakfast, lunch AND dinner.

Jamie Hall

I hope you are doing this because someone is forcing you to do it. It's pretty close to the worst and most expensive heating change you could possibly make.

As @Steamhead said, though, Con-Ed will just love you.

As for "capping the steam pipe", no. Even if you installed multiple safety devices to prevent the boiler from ever steaming, the air trapped inside and the water will expand, and that has to go somewhere. In my humble opinion, absolutely not safe. Scrap the boiler and the hot water coil, and install a nice electric water heater while you are at it.

Don't say we didn't warn you.

Mad Dog_2

Do you know how expensive a Kilowatt of Electric from Con Ed is?  Do your homework before you make a drastic mistake.  Steam and Hydronic heating is the most comfortable.  Mad Dog  🐕 

BronxMatt

Sorry guys i guess i should have realized i’d hit a nerve by talking about switching to electric in the steam heating forum! I appreciate and actually agree with the concerns you raise about electricity costs but part of the reason i’m doing this is to move from one system where i pay the oil bill, to separate systems that my tenants pay for on their own con ed bill, so electric cost isn’t really my concern here. 

But it sounds like this is not safe. What about removing some but not all of the radiators? Can i cut and cap the pipe leading to a radiator so i can remove it? 

Jamie Hall

OK. Always helps to have the complete picture. Yes you can remove some of the radiators (and cap their runouts) but that, of course, will leave the boiler well oversized, which isn't all that economical.

In your situation, I also might consider going to all electric -- but as I said earlier, go the whole show, and if you want to pass the energy costs to the tenants, pass all of it: get individual electric water heaters for each unit.

109A_5

I would fear I would not have any tenants after the first Winter. Or have to reduce the rent to compensate, it may mess up the building's economics. I'd be careful with the overall strategy.

That being said is there a special electric rate for all electric residential heating ? Not sure if heat pumps are applicable or just resistive heat.

BronxMatt

@109A_5  Con ed offers a $3,000 rebate per rental unit when decommissioning gas or oil heat and replacing with heat pumps. No special rate for electricity but supposedly heat pumps are efficient. 

In any case they will be more efficient than the 120 year old boiler in my basement, and this steam system that only has two radiators per floor ( half the rooms don’t have radiators and were meant to rely on an open railroad layout, which i have since closed into separate bedrooms. That means i’ve been relying on electric space heaters; both inefficient and dangerous.)

Yes i will likely have to offer a slightly reduced rent since heat is not included but that’s fine. 

BronxMatt

@Jamie Hall Thanks that’s helpful!  

Since i won’t be using the radiators at all, it won’t matter that the boiler is oversized. It will only be providing hot water temporarily until i replace the hot water heater. 

pecmsg

Keep those space heaters available for the heat pumps down time.

Jamie Hall

The rebate offered might cover the additional cost of the electricity ... for the first year. In your area, a heat pump will cost about the same as a decent oil or gas boiler to run, since they do use less electricity than straight resistance (but not enough less to cost less to run). Straight resistance, which is cheap to install (assuming you have adequate electrical service -- do you?), will run three to four times what the oil or gas would cost.

As @pecmsg said, however, you will need some resistance heat if you do use heat pumps. Unless I am mistaken, you are required by the code to be able to maintain 72 degrees minimum -- and heat pumps alone won't do that. The resistance heat may be built into the heat pump, depending on the model.

Mad Dog_2

Do your research and due diligence....once the boiler, pipes, and radiators are gone, your options are GONE...forever.  mad dog 🐕