Piping for New Steam Boiler

Noah_1

@delcrossv yes, already bought. I believe a further reduction of the EDR of 20% and pickup reduction would make the unit oversized by at least 20%. I will rerun the numbers but could I run it at a lower pressure? Also FYI home is quite drafty, no insulation, single pane large windows, etc.

delcrossv

https://forum.heatinghelp.com/discussion/comment/1842245#Comment_1842245

@Noah_1 could be worse. Pressure control is now critical. At least it's not grossly oversized.

What model boiler is it? There's always a possibility of downfiring if it turns out it's short cycling too much.

I'd install it as is with a vaporstat as the operating control. If it's short cycling on pressure , there's the downfire option.

The boiler will only "see" installed radiation, heat loss in the rooms is managed by radiator sizing. Probably with a 1920's house the radiation is already oversized for the heat loss. Moreso if you subsequently tighten things up.

Noah_1

@delcrossv I will send you the numbers soon.

Noah_1

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????

delcrossv

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! 🙂

delcrossv

@Noah_1 What's your brand and model of boiler?

Noah_1

@delcrossv I used square feet and mutiplied by 50 to get crude (zone 5) and measured actual radiators to get EDR (assuming radiators are sufficient for rooms they are in…calculating room requirements now). I thought since pipes were not insulated that one needed a pickup factor, that’s where I added the 33%. You suggested 10-15%. So even with that. it puts us around 8-12% oversized. Can your explain how that jumped to 33% oversized, seems substantial? The home is quite large, drafty, with many large windows. It’s a Utica peg299eid. As for water level, just wanted to confirm that it will land or coincide with Lwco, landing it 2 inches below middle of glass gauge or about 1/4 from bottom of glass gauge. Thanks for the feedback! As for the boiler, are you suggesting it will cycle frequently with vaporstat?

delcrossv

@Noah_1 2 questions:

1. What was your sq.ft. of steam number measured off your radiators?

Here's your boiler's EDR output including a 33% pickup factor- so the actual output is 1/3 more.

782 sq ft.

2. How does that compare to your measured radiation- in square feet?

Don't get hung up on heat loss or BTU's . Just Sq. Ft of radiation to Sq. ft. of boiler output 😉

Doesn't look like the pipes are insulated so you can write off the pickup factor (mostly). How well that 782 sq ft. matches your measured radiator EDR is what's important.

At the risk of sounding dumb, sq ft of radiation is the surface area of your rads, not the size of the rooms. (Seems your 200k number / 50 is the size of the house- 4000 sq ft)

Noah_1

@delcrossv

For clarification…three measures I was dealing with . The initial was just crude. Square feet of home multiplied by the 50 and that produced a crude measure of 200k btu needed for the home (not taking any variables into account). What’s more important and more tedious to calculate was the btu produced by the radiators (square feet) and that will also be dependent on room requirements (width, length, ceiling height, windows, floor below and on top heated/unheated etc). The latter is what I am currently working on to make sure the radiators that are in the rooms are sufficient for the spaces (some seem to have been changed and not original to home), hopefully some are smaller and can be increased to not only heat spaces better, but to offset the oversize. Once I determine that, then I will recalculate my radiator sq feet radiation which I have currently as 740.1 for those that are currently in place (assuming they are all sized properly). The radiators going in remaining areas will add another 100-150 guesstimating for now (again assuming all those installed are sufficient for the spaces).

delcrossv

@Noah_1 Hang on:

"What’s more important and more tedious to calculate was the btu produced by the radiators (square feet) and that will also be dependent on room requirements (width, length, ceiling height, windows, floor below and on top heated/unheated etc).

NO! For boiler sizing, none of that matters (unless you're starting from scratch) EDR is just based on the type of rad, length x width x height and the number of sections. That's it. Hot water would require that but steam works off latent , not sensible, heat so the output is fixed by how much steam the installed radiation can condense- regardless of where it's put.

Did you look up your rads as to type and measure them and add sections up to get your 740.1 number?

I'd be really surprised if you're grossly under-radiated. Probably the opposite.

Noah_1

@delcrossv In a way I am starting from scratch, at least when it comes to the radiators that were disconnected (as in removed). I have to calculate the space in those areas and make sure the new radiators’ btu aligns with requirements of the room/space. In other parts of the home radiators were previously changed (don’t seem to be original to home) and I want to make sure they also satisfy those spaces. As for the radiator EDR, yes! I already did exactly what you mentioned. I looked up the radiator type (tube, column etc), did the math, and got the 740.1. Hope this helps.

delcrossv

@Noah_1 Great! Thanks for verifying. In that case, you're in the ballpark for boiler sizing.

To your other question, yes, you may still cycle on pressure, so I'd really recommend a vaporstat. Lack of rad traps makes pressure control in the ounces range pretty critical in this system.

You will also need to check the replaced rads/valves to see that they have orifice plates installed.

👍️

Noah_1

@delcrossv Glad to hear that! I will keep you posted.