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Hi @delcrossv. In close inspection of all radiators, found what you had been hinting at all along. See attached. Also the home is just over 4,000 sq ft so crude measure I got given climate zone, gives EDR requirement of around 200k btu. And I used pickup of 1.33 and got 266k btu. But given you suggested a reduced factor despite the older, uninsulated home, I got 230k btu. So that’s about 8% oversized rather than about 8% undersized as I was calculating. Now the rad EDR for those connected is around 180k…but that’s without all the connected radiators and with connected radiators it’s going to be around 200k btu but no pickup added. With conservative pickup of 15% instead of 33% we end up with 230k btu.

On a side note, working on Hartford loop and it’s usually 2 inches below water line. There seems to be confusion online as to where to place it with regards to waterline. 2 inches Below max waterline, or min, or middle…I’m under understanding of 2” below operational or middle of glass gauge????

Hi @Noah_1! Did you get your EDR by measuring the rads or doing a heat loss? Steam isn't hot water and steam EDR is the connected radiation only, not building heat loss. If you need help calculating EDR off radiator measurements, we can help.

Assuming you have 200k of connected radiation, you don't need to add a pickup factor to your EDR measurements as that's baked into the boiler rating. So using your 200k number you'll be about 1/3 oversized with your 250k boiler, but not grossly so. Your system will cycle on pressure so getting a vaporstat is pretty much a no brainer.

Your boiler I&O manual will spec where the Hartford Loop should be located, but it will be no lower than your LWCO limit (usually). If the manual isn't clear it's 2" below the operating WL- middle of the glass.

If those valves are all through the house, and they work, the regulation is built-in. A little PB Blaster on the valve stem often frees them up. Tunstall may make rebuild kits for these if they're completely fried, but you'll have to contact them.

You'll need to keep the pressure low enough to ensure the valves don't admit more steam than the rad can completely condense. A lot lower than a regular pressuretrol can provide.

You may need to open up the return elbows and remove stuck bafflers if a rad won't heat. It's a common failure mode.

Keep us apprised as things move along! 🙂

I just wanted to thank y'all again for taking the time to respond over the weekend.

I'm sourcing some insulation to start with. I'll make incremental changes after that

@Noah_1 No, you're replacing the vacuum controller with vents. Basement pipes should be as we discussed.

The system should work fine if:

The inputs on the rads are metered so you get full condensation and

The pressure is low enough so that can happen without losing your water seals

For the rads that were disconnected, were any orifice plates found? Do you see a check plate (baffler) in the return elbows?

Important:

Is the new boiler already bought? Reason I'm asking is the effective EDR for this system is only 80% of the measured EDR (due to the metering and full condensation requirement). You may also consider dropping the usual 33% pickup factor to 10-15%

Here's a table of orifice sizes I found here that specs sizes by EDR and pressure if you have to replace them.

I don't think the table has the 20% EDR reduction built in.