Can I convert this single pipe steam system to gas?

tsquared

We have a Weil McLain P-SGO-4 series 2 boiler with an integrated tankless hot water heater. The water heater doesn't work for beans (can take 10 minutes in winter to get warm then it alternates between freezing cold and scalding hot for lengths of time, which makes for a miserable shower). We need to replace it before the cold weather comes and are considering bypassing this system and installing a wall mounted, direct vent tankless gas water heater (possibly the NORITZ NRC661-DV-NG) as there is no space in our basement for a 40-50 gallon tank.

On the other hand we are also considering getting rid of the giant WM beast we have and converting to a gas steam boiler, which would also free the space the oil tank currently takes up, scoring us more storage in our tiny basement and could eventually mean being able to get rid of the center chimney and reclaiming that space for our bathrooms upstairs.

Our system is single pipe, steam, cast iron radiators - there are 8 of them. Two are very long in the dining and living rooms downstairs (as seen in the picture), 2 are very small (in the bathrooms on each floor) and the other 4 are medium sized in the bedrooms and sunporch. I'd like to avoid having to replace the radiators because of the cost and would also consider another combo system if it would work with what we have. Of note is that we would be eligible for substantial rebates from our utility and can qualify for 0% financing of the conversion, provided the EF/AFUE ratings of the unit(s) meet the efficiency requirements of the program. For reference we live in Massachusetts, the existing WM boiler is approx 25-30 years old (water cut off valve was replaced about 6 months ago), the house is a Cape built in 1939 and is about 1150 sq. ft. We have gas service to the house and I've included a picture of that as well - the pipes appear to be 1" OD.

Is gas conversion even possible with a single pipe system? Would something like the Bosch ZBR 16-3 combo unit be appropriate?

I'm having a hard time sifting through all the information out there. Any advice from the steam folks on what our options are would be much appreciated. (This pains me as my dad was a steamfitter, and excellent at his trade but he is sadly no longer with us) Thank you in advance for your expertise and opinions!

tsquared

Forgot to add the picture of the gas service! Pipes might even be 1-1/4" OD

New England SteamWorks

Well...Let us tackle this one problem at a time.

First the easy part: Of course you can covert to a gas steam boiler. That seems to be a pretty popular thing to do these days, and lord knows I've done my share of them. When comparing gas to oil it is pretty pointless to consider the price of the fuel. And before everyone gets all hoping mad, there's a thing called a Futures Market where people far wiser than us bet on the future prices of gas and oil. One look and you'll see even they do not know. If anyone did, -they'd be very wealthy indeed.

Beyond that, the case for gas is a cash flow one: Use the gas first, pay for it later. Can't pay? In most instances it is illegal to cut you off during the heating season so you'll still be warm. With oil you pay first and use it later. Not such a big deal with homeowners, always a bit of a hassle with renters.

The benefit of oil is me, and the thousands of guys just like me. We care about you. Our business model depends on you. You're part of our family and our greatest priority. The gas company could care less about you, and if you have a problem during a cold snap, the average gas service company isn't going to prioritize you because there's little repeat business involved, let alone a relationship.

Having said all that, you already have gas to the house, and an oil tank does take up space that apparently you could use. Not sure how the central chimney fits into things, as you will still need a chimney with steam heat.

Next there is this: Why are we replacing the boiler without knowing why the hot water is problematic? I'd think you would want to get to the bottom of that first, before making further decisions. Could be something simple.

And lastly, good things could come from a new boiler. The current boiler doesn't have the best piping, may be incorrectly sized, and likely has very poor main venting, not to mention no insulation that I can see. Gas or oil, you're in for some savings with a new install.

jumper

Gas is less smelly. It doesn't involve a fuel pump to go wrong. And in my day you didn't need a blower,another dingbat to go wrong and make noise.

New England SteamWorks

I forgot to add: The highest efficiency rating for a steam boiler currently is the Burnham MegaSteam, which is 86% and a very fine boiler indeed. The best residential steam boiler, IMHO. It is oil only. Atmospheric gas boilers are in the 82-83% range, if that helps your rebate (or other) calculations.

Jamie Hall

Sort of echoing @RI_SteamWorks -- who is very knowledgeable, by the way, and in your area sort of (as are several other top drawer folks, @Charlie from wmass for one).

First, I wouldn't worry too much about the rebate thing. As RI said, the best steam boiler out there in terms of rated efficiency is the Burnham MegaSteam at 86%. Others are rated a little lower-- although they can actually do better, properly maintained. Unfortunately the paper pushers in Boston don't recognise that, and they may not give you a rebate at that efficiency point.

However, the only way to go higher is a mod/con hot water boiler, and that you do not want to do. The cost of conversion -- even if everything went perfectly -- would eat up the rebate and then some.

OK. That said, gas vs. oil. That's a toss-up. There are advantages to both, but on the whole I agree with RI's comments on the subject. The only real downside to oil is the tank; how much of a hassle that is depends entirely on you. (And with apologies to @jumper -- oil doesn't smell unless you have a leak or drips, which you shouldn't!)

Now hot water. There is a good deal to be said for the tankless units -- but you might have to increase your gas line size (you would for a gas fired boiler or a conversion burner anyway). However, it might be something as simple as a bad control -- in fact, that's what it sounds like from your description. Keep in mind, though, that if you were to keep the oil oil fired hot water heaters are available, and even a 40 gallon unit will keep up with all but the biggest McMansions with four teenage daughters...

Steamhead

That tankless coil is either plugged or the tempering valve or flow restrictor is bad. Nothing wrong with the boiler itself.

You would definitely have to increase your gas service capacity if you used a tankless water heater. Not sure how your utility handles upgrades, but in my area BGE can be a real nightmare. From the looks of that meter, you should be able to operate the boiler, water heater and a gas kitchen stove without having to upgrade it.

You don't show your oil tank, but if it's not far you could make room for some of your shelving when it's gone. That would leave room for a tank-type water heater venting into the chimney.

I wouldn't be so quick to try to remove the chimney. It has no moving parts and, if properly lined, will outlast all of us. Without a chimney you need some sort of fan-driven venting device, and in my experience these always break down on the coldest day of the year.

If that were my job, I'd convert your boiler to gas using a Carlin EZ-Gas burner and the various items that would complete the job, such as a gas-type barometric draft control. Then I'd abandon the tankless coil and install a tank-type water heater. Simple and durable. Then I'd check your main venting and other things that will make your system use less fuel.

And you can't go wrong with either of the two choices mentioned above, @RI_SteamWorks and @Charlie from wmass.

tsquared

This is all very good advice, thank you. I will reread this evening and discuss with the husband. Rebates for oil equipment upgrades in Mass are only 30-40% of the gas-related rebates so that won't make a dent. We don't have room for a tank water heater if we keep the big oil boiler as it's in the center of the room with a utility sink and laundry on one side, doors about 3 feet away on 2 sides and the path to yet another door on the 4th side. The oil tank is about 8-10 feet away in the far corner next to the back door (there's an ugly lump on the floor of crumbling concrete doing a poor job of covering the line between the tank and the boiler). Sounds like our first move should be to have the tankless coil, tempering valve and/or flow restrictor looked at. I'm loathe to pour more money into this system though as it's ancient and as said above likely isn't well piped or vented. Is it really true that we can't get rid of the center chimney with a gas unit? I thought we'd be able to direct vent that out a side wall...

Sailah

Going through the Mass Save program myself right now. In fact the insulation guys showed up this morning to do my walls and attic.

I would start off with finding a contractor you trust and let their recommendations help guide your decisions.

As I am sure you know there are much larger incentives for gas equipment because of the utility's involvement in rebates.

I wish I was pondering what the best steam system to install would be, but I'm stuck with forced hot dust so consider yourself lucky!!

SWEI

Power venting through a sidewall adds cost, complexity, and moving parts that wear out. More things to break, more service required.

The masonry chimney could be replaced with B-vent in a chase for a gas appliance. Could make sense, especially if it's part of a major remodel -- though you do need to make sure the existing chimney is not providing structural support.

Charlie from wmass

Side wall,chimney, power venting are all options. Upgrading the boiler may save space depending on how accurately the existing boiler is sized to your system.

JUGHNE

Ancient is a relative term, I maintain a 1955 steam boiler which will not go away until the building is torn down. Do you know the age of your boiler? The serial number may show the year.
As long as it holds water it will work, a new steamer would not be much more efficient than what you have. Everything, new and old, must be installed correctly and maintained.

With the oil tank gone you may have room for a separate gas water heater tank. It could be side wall vented pretty easily.
Some boiler side wall vents have been noise issues sometimes.