Steam to Hot Water?

[John Molyneux]

Hi All: I'm helping a neighbor with a heating system decision. Her situation is:

Small cape in southern Maine
Hasn't had a heat loss calc done but it has to be less than or at most equal to mine (30,000 Btu/hr)
Maybe some insulation but she's not really sure (I obviously recommended an energy audit, since it's covered by rebates)
Current system is 30+ year old single pipe oil-fired steam
200 gal. oil tank in questionable condition with difficult access for getting a new one in the basement (and she kind of wants to get off oil, anyway). But she could probably get away with a smaller tank...
Only used 200 gallons of oil during 14/15 winter
Supplements with stand-alone pellet stove
Stand-alone 40 gal. electric HW
Natural gas being installed on our street this summer

She's getting wildly differing opinions from the several contractors she's had look at it. One still installs steam but says they'd need to re-pipe the radiators, and the quote was expensive. The contractor I used (who I really like) doesn't do steam anymore and recommended conversion to hot water with panel radiators, but that quote was very expensive. She also looked at mini-splits but decided that wouldn't be a good fit for her situation.

Nothing obviously wrong with her current system except age (probably the original boiler) and the fact that the oil tank is sketchy (it's already been patched). Not sure who made her existing boiler but she's been told it can't be converted to gas.

She's not uncomfortable and it doesn't seem like she'd see any kind of payback based on her current fuel use. Should she stick with the current setup until it dies of natural causes? Is there a less expensive, more creative hot water or steam option? Other?

 

[BadgerBoilerMN]

Conversion from steam and to gas is a natural.

We use condensing water heater with a sub-system for radiant heat. We also design and/or install all sorts of radiant systems for small home, cottages and cabins. The wall-hung panel radiator e.g. Buderus, DiaNorm, Myson et.al. will keep you warm and give you individual room control. The fuel bill should go down by half if properly sized an installed.

The payback is in comfort and peace of mind.

 

[Sponsor]

 

[Dana]

Since she's been using the pellet stove it's harder to do the full fuel-use heat load analysis without some precision on both the oil & pellet use. Most pellet stoves put out well over 30,000 BTU/hr, and even if she used the steam boiler as the Hail Mary backup it's likely that most of the heating was done with the pellet stove.

At low loads and recently lower fuel prices, limping along with a 50% as-used AFUE steam system used primarily as the backup for a pellet stove it's hard to make a financial case for converting to a new boiler. If it were 2-pipe steam the retrofit would be pretty easy (but it ain't), but at only 200 gallons/year a boiler swap isn't going to be worth it until it's necessary.

The high price of the panel radiator retrofit solution is largely the installed cost of the radiation. Cheap fin-tube baseboards are a small fraction of the cost (and a small fraction of the comfort levels provided ). Heating with gas is probably going to be cheaper than with a pellet stove, and it's certainly easier to just tweak the thermostat than it is to lug & load sacks of pellets. (I have a 5'-nuthin' co-worker who heats primarily with a pellet stove, but handling the bulk fuel is getting to be a bit much for her now that she's north of 60. and not quite in the same shape she was back in 1985 when she bought the place.)

It's always worth tightening up and insulating, the house, no matter what the heating source, and $25K of building thermal envelope upgrades would be money better spent than dropping the $25K+ on a new boiler + radiation as long as the current system(s) is (are) working for her.

With the antique steam system it's worth testing/replacing the main system vents and the radiator vents on the 1-pipe system every few years. It's not worth re-piping a steam system (other than replacing the Hartford loop/wet return sections when it rusts out, which it will.) If the rest of the steam plumbing is in bad enough shape that it needs replacing, it's time to kiss the whole system goodbye.

A mid-efficiency 2-3 plate cast-iron boiler plus fin-tube baseboard and an indirect HW heater should come in at less than $10K in a competitive market. A half-dozen years ago the antique steam boiler in my niece's place crapped out (after only 95 years of service?), and I helped get her set up with 2-heating zones and an indirect with a power vented 3-plate Burnham for about $7K. We had solicited quotes for either an all-new hydronic system with baseboards or a replacement for the steam boiler. The lowest steam boiler replacement bid came in a bit over $8K, and did not include a water heater. Key to keeping it bounded was having done the heat load calculations ahead of time, and telling the contractors what she wanted rather than asking them to conjure something up. It would have been a ~37K input 2-plate atmospheric drafted boiler with a new chimney liner, but the local boiler distributor was out of stock at the time, and the 3-plate ~60K power vent ended up being a few hundred cheaper anyway, since it avoided the cost of the liner. It wasn't ideal, but it still only uses about half the gas than the kludged-up circa 1982 retrofit gas burner bolted to the sealed up coal-feed firebox door on the pre-1920 beastie boiler. (I suspect an oil burner preceded the gas burner for a few decades, but don't have sufficient history to know for sure.)

 

[Dana]

Conversion from steam and to gas is a natural.

We use condensing water heater with a sub-system for radiant heat. We also design and/or install all sorts of radiant systems for small home, cottages and cabins. The wall-hung panel radiator e.g. Buderus, DiaNorm, Myson et.al. will keep you warm and give you individual room control. The fuel bill should go down by half if properly sized an installed.

The payback is in comfort and peace of mind.

True that!

But at what price in US dollars?

Until she's ready to stop lugging wood pellets it's hard to make the financial case for replacing the boiler even with the peace of mind aspects. Even when the boiler lays down and dies, she's not going to be cold.

I suspect the fuel price would go down by half just moving to mid-efficiency gas right-sized for the load, but that depends a lot on the local price of pellets and the efficiency of her pellet stove. Swapping to a barely-legal efficiency gas fired steam boiler would probably cut the heating cost by almost half too.

Half of an already small marginal operating cost is just smaller, and half nuthin', is still nuthin'. The upfront cost of any full system is not small. She has to WANT that peace of mind badly enough to pay for it.

If it were my house (and it isn't), I'd be rid of the oil burner no matter what, if only to buy back the space in the basement and limit the risk of having to pay for an oil leak clean-up down the road. The particulate matter emissions of an oil burner are orders of magnitude higher than a gas burner, but still orders of magnitude lower than the PM2.5 you get out of a pellet-burner, so the local air pollution argument probably isn't going to work here.

 

[John Molyneux]

The going rate around these parts (ballpark) seems to be around $8k - $10k for upgrading an existing HW system to a modcon and $20k to fully retrofit single pipe steam in a small-ish house with panel radiators. Careful shopping, rebates and various incentives can obviously affect that. Before I started my project I thought $8k sounded awfully high until I saw how much labor -- and craftsmanship -- goes into a high quality installation.

Speaking of which -- here are a couple pics of what I just had done. Thanks to all of you for helping me get educated.