Running water loop on new steam boiler

Steve Garson

I need to replace my 70 year old steam boiler this summer. The quality of the heat is fine and balanced, but I need advice on how to handle the hydronic loop:

1. One room has 30 feet of baseboard with the loop heated from the steam boiler (with tempering to avoid flashing to boil). This is simply tapped off the boiler. Can I do the same with a new steam boiler which will have 2 or 3 fewer gallons? I measured the present water capacity at almost 18 gallons. Should I get a tankless coil and run the loop off of that? An indirect tank?

2. I have a room with 12,000 BTU heat-loss heated with a radiant loop that is heated from a Bradford White gas water heater (designed for both a potable and heating loop). From an energy efficiency perspective, should I include this into the equation, or just leave as is. I would love to stop having to manually lower the heater temp when the whether is warm before I become an old man :) Does anyone make a tempering valve that can use an outside sensor for this loop?

Thanks for all the insights guys. I love this site!

Steve

DanHolohan

Please read this:

Hot Water Zone

It pays to wander off the Wall.

gehring_3

Question for Dan

I read your article and studied the piping diagram. If such a zone were to be used in the basement so that the entire system is situated below the waterline of the boiler would it be adviseable to create a loop of pipe on either end (feed and return) like a Hartford loop, to prevent loss of boiler water in the event of a leak? I've seen some piping diagrams from boiler manufacturers and they show a check valve, but I thought there is a potential problem with check valves in steam boiler systems possibly getting stuck open with scale or rust. Wouldn't a mini Hartford loop on either end be more fail-safe?

Just a thought.

Steve Garson

hot water loops off steam boiler

Dan - My present water loop off my boiler follows what you describe in the article, which works fine. The heat loss in the room that has that loop is 13,000 BTU.

The radiant loop that now uses the water heater has 12,000 BTU of heat loss. If I add that to the boiler, the total would be 25,000 BTU. Your article seems to indicate that I can go as high as 40,000 BTU.

A new steam boiler will be sized for the 461 square feet of radiation, so a WM SGO-6-2 with 542 Sq Feet Net IBR rating seems to fit, since the next smaller provided 450 Net IBR.

With the above info, can I run both hydronic loops on the new steam boiler?

gehring_3

Loop vs. Check Valve


This thread was about to go off the wall...I would still like to hear from an expert on the opinion of an actual pipe loop versus a check valve as described/questioned above. Thanks

Kal Row

dan is a busy man....

if you read all his books, the answers are there, or at least, you will have been imparted with enough smarts to figure it out for yourself

quickly:

use high torque bronse pumps

heat exchangers are better but use shell and tube - flat-plate will get clogged with boiler sludge

dont need check valves if you can control the gravity flow with heat traps in-line, like 2ft upsidown U-tubes

brass spring checks wont get stuck or make noise, if you put it past the pump with 12 straight/smooth pipe diameters preceeding it

dan will correct me if i screw it up

DanHolohan

You could do that,

but it might be a source of air-binding.

Kal Row

correction: top upsidedown u below water level in boiler..

see dan's air binding issue above - might still work as heat trap - especially if your u is starting at the floor - once you get the air out - it should stay out

"below water level in boiler", that is, below low-water cutout point - or you havent dun-a-thang