Advice on steam or forced air

duncaorc

I'm looking for help. We have a house from 1925, built single story with steam radiators. The former owner built out the attic and installed a furnace and AC unit that has vents on both floors. Thermostats for both the boiler and the furnace are side by side on the ground floor. In summer, we need the AC on both floors. In winter, we have to run both systems to get even heat, because there's only one radiator on the second floor.

Then the boiler cracked. Most places are telling us to scrap the steam system and zone with a whole new forced air system for the ground floor. The cost seems to be the same to replace the boiler or tear it out and put in forced air. Are there technical or other economic reasons to choose one over the other?

Steamhead

You've probably noticed that the part of the house with forced-air is less comfortable in the winter than the steam-heated portion. Keep the steam.

If that were my house, I'd install radiators on the second floor and run steam pipes to them.

MilanD

Home owner here...

It seems so unfair to be in the situation you find yourself in, having to choose one because of the economics... I personally live in a brick 1911-built home with a furnace. At work I watch over a 1 pipe steam system on a 10.000 square ft building (also brick) and CI rads, and also have some brick rental properties, some with hot water and copper finn in-wall emmiters, and some with hot air furnaces... You just can't compare the hydronic heat to hot air when it comes to comfort, and steam is just great when it comes to how it feels in the winter compared to water... I am looking into installing steam in my house despite the furnace already being there... I absolutely hate the furnace, and hate cold brick interior walls in the winter. I live with it, but knowing for better - passionately dislike it.

Now back to economics. You will be "warm" with the furnace, no doubt... But it will never feel the same as steam heat, and you may have noticed the difference too, as @Steamhead suggested. If you can run pipes to rooms without them now, just pretend you are the one who did the addition and bite the bullet and add rads and pipes where there are none, and replace the boiler. If you can't afford it, then you have your answer. Think as if you are choosing between repairing a Cadillac or replacing it with a Kia because the engine block cracked on the Caddy. Both cars will get you from A to B.

Properly maintained boiler can last for a long time, although do be aware, the steam system does need a good steam man who knows how to properly install it and also a homeowner willing to learn about steam to keep a good eye on it. How/why did the current boiler crack, and how old was it? Will replacing the boiler also fix the system and does your tech know how to optimise it?

Also, the fact your hvac tech tells you to rip out steam tells me he is not the only tech you should be having in your house looking at this.

It's a tough one... I would probably fix the boiler if that's what broke down, and make sure all the components of the system function as they should, to prevent conditions that cracked the current boiler. Then I'd look to add rads to where there is none at a later point in time. In any case, I would not use the guy who suggested ripping out steam, and would make sure new boiler is sized to the future load.

It's a tough one and I feel for you... Best of luck!

HVACNUT

First, let put on some body armor for when the steam guys club me.

Does the furnace satisfy the house in winter without the boiler?

Replacing a steam boiler, and adding sufficient radiation to the 2nd floor will cost about the same as a furnace with A/C for the 1st floor?
I would love to see the side by side estimates for that.

Does it get warmer upstairs in summer and winter because the thermostat is on the 1st floor?

I'm assuming that there's not a trunk duct dedicated to the 1st floor, but a main trunk duct with branch ducts dropping to the 1st floor where feasible.

Consider zoning your existing furnace with A/C in the attic (if it can satisfy the whole house without the boiler).

A properly zoned system (with a quality steam humidifier) can be a comfortable, cost effective alternative.

If there are dedicated trunk ducts for the 1st and 2nd floor, a standard 24, motorized opposed blade system will work.
If there's one main trunk duct, then an Arzel zoning system is the way to go.
It's a neumatic damper system that will have dampers in every branch duct to separate the 1st and 2nd floors.

In either zoning application, a barometric bypass must be installed.

A quality steam humidifier is a must. Preferably with an outdoor air sensor.

Something to think about.

Danny Scully

Where are you located @duncaorc?

duncaorc

@Danny Scully We're in St. Louis. We've noticed a tendency here to replace radiator systems generally, and there's not a ton of people here who are willing to work with steam.

The boiler is 35 years old. It's definitely got a crack, but we don't know what caused it. We moved to the house a year and a half ago.

@HVACNUT Upstairs has two bedrooms, a bath, and a small open space, but only one radiator in one bedroom. If we run the FURNACE ONLY, the upstairs get too hot. If we run the BOILER ONLY, the upstairs stays much too cold. So the only way to get both floors comfortable is to run both systems. That's not necessarily a problem, but if I have to put in a new boiler, it seems like a good time to optimize the system. The furnace/AC system also needs some duct work redone and more air vents upstairs to balance it out. Right now, it's loud in those upstairs bedrooms because of the blower and leaky ducts in the knee wall and the one bedroom is always stuffy.

My initial thought was to add two radiators upstairs in the rooms that don't have them, but the one tech I asked said it would be difficult and cost prohibitive.

We've always had radiators, though all hot water before this house. I hate to move away from them. But I also want a system that works.

Steamhead

duncaorc said:

We've noticed a tendency here to replace radiator systems generally, and there's not a ton of people here who are willing to work with steam.

(snip)

My initial thought was to add two radiators upstairs in the rooms that don't have them, but the one tech I asked said it would be difficult and cost prohibitive.

Let me guess- that same "tech" was trying to get you to tear out the radiators?