Replace 70 ? year old - oil fired H.B. Smith Co. Steam Boiler with gas fired Hydronic Combi?

Nativebostonian97

House built in 1950. I believe the H.B. Smith oil fired steam boiler that also has internal tankless for domestic hot water is original . Model #S0B S5, Serial # 135S. Appreciate if anyone can decipher age from Serial #.
Looking for advice. House has natural gas. Do I replace with gas fired steam boiler or install new Gas Fired Hydronic Combi. Thought is to keep the cast iron radiators, rip out the single pipe cast iron piping runs and replace with 3/4 inch copper and or pex to radiators.
House is very small, recently remodeled down to the studs = 2 bedrooms, 5 radiators total. Appreciate input, advice - Thanks ! - Nativebostonian

JUGHNE

Not all steam radiators can convert to hot water.
Pictures needed if you are not sure.

Hot water will deliver less heat than steam to the same radiator.
If you have upgraded the insulation envelope that may not be a factor.

Myself, I would not do the combi. Rather a boiler with indirect tank for HW.

Jamie Hall

Keep the steam. That's easy. Replacing steam with hot water sometimes works well... but not very often. Amazing how many leaky radiators turn up when you fill them with water at 15 psi instead of steam at 1 psi (if they are even usable for hot water -- not all of them are)(plus they all have to be converted to hot water piping, even if they are otherwise usable...)... then there's the cost of all new plumbing, plus the new boiler. If you keep the steam, all you need is a competent installer and the new boiler.

Presumably you insulated the dickens out of it when you did the remodel, so the good news is that the much lower output of a hot water radiator compared to a steam radiator might not be a problem...

bburd

Agreed, keep the steam.

That's a good sturdy boiler, but at that age it's close to done. If the house was built in 1950, those radiators and steam pipes have decades of life left (assuming the pipes are properly pitched and have not had pools of water lying in them for years).

You may need to consider replacing the wet return pipes, which have a shorter life than steam pipes because the  condensate is slightly acidic.

Nativebostonian

Gents,
Thanks ! - So appreciate the advice & expertise. Attached photos of radiators ( 5 total ). The house is tiny -2 bedroom. Last year stripped to studs inside and out. New roof, shingles, very well insulated, new widows, front & back doors, including expensive storm doors. Ran out of money for heat replacement. I have promoted myself to a class B+ plumber so I would re-pipe the radiators if you think they are worthy via the pictures. Jughne, I agree with you. I put Burnham Alpine Condensing boilers in my girlfriends, and son's house coupled with HTP Indirects and just plenty of hot water for domestic & trouble free. What has me even thinking of a Combi is the rave reviews of the Weil McLain Eco Tec and that the house has just 1 bathroom. Anyhow, will figure that out. Another driver for hydronic is MA Save = $1,600, rebate for condensing hot water boilers, $400. for indirect. Up to $50K interest free loan with 10 year payback window.
Appreciate if you gents can look at the radiators and let me know if they should work for conversion from steam to hot water.

Jamie Hall

Well, at least the radiators which one can see are connected across the top -- so they can, in principle, be converted to use hot water. That doesn't mean they will withstand the additional pressure; I'd give them a perhaps 50/50 chance on that.

One thing you should do before you go any further at all is do a room by room analysis of the heating loads, and then determine the heat output of the radiator in each room and compare that to the heating load. Remember that the 240 BTUh per square foot EDR is based on steam at 212. You can get a decent first pass of the heat output at other hot water temperatures by doing the following. Subtract 82 from the hot water temperature, and multiply the result by 1.8. The result is the heat output in BTUh. It isn't exact, but it's not bad for a first pass.

The point of doing this is to determine at what water temperature you will have to run your hot water system to obtain adequate heat.

You can run an indirect off a steam boiler just as well as off a hot water boiler. Same basic hardware, same controls.

Now to those free goodies from the state. I hate to be a spoil sport, but by the time you have added up the cost or ripping the old pipe out, reconfiguring all the radiators for hot water, and installing the new pipe, you will have burned through a good deal more than those wonderful freebies you mention. Worse, the results of the heat output study may show that you can't use a condensing boiler effectively, so the extra cash you spend on that boiler and its controls vs. a simple steam boiler replacement will also be wasted. I might also note that "interest free" doesn't mean you don't have to pay it back. You do.

It's your money, and your call. I wouldn't do it, and I wouldn't recommend doing it to anyone else.

EdTheHeaterMan

That is not the original 1950s heater. That heater has 1970s or later clues all over it. The riser with a union has teflon tape on the threaded joints. The pipe coupling is malleable not cast. Package boilers designs like that were just getting introduced in the 1960s. Smaller "Mini pump" Webster fuel pump. Top opening ignition transformer for nozzle access. These were not the normal oil burner set up in the 1950s but more like the 1960s and it is unlikely that someone would install a new boiler within 10 to 20 years of the original, unless there was a problem with the original boiler. My guess is the late 1970s. And I would stick with Steam if I were in that house. I might get a separate water heater, maybe an inexpensive 40 gallon atmospheric gas automatic.

EdTheHeaterMan

Nativebostonian97 said:

House built in 1950. I believe the H.B. Smith oil fired steam boiler that also has internal tankless for domestic hot water is original . Model #S0B S5, Serial # 135S. Appreciate if anyone can decipher age from Serial #.
Looking for advice. House has natural gas. Do I replace with gas fired steam boiler or install new Gas Fired Hydronic Combi. Thought is to keep the cast iron radiators, rip out the single pipe cast iron piping runs and replace with 3/4 inch copper and or pex to radiators.
House is very small, recently remodeled down to the studs = 2 bedrooms, 5 radiators total. Appreciate input, advice - Thanks ! - Nativebostonian

Sometimes the model name like SmithPac or Century series will help to identify the age. What does the sticker on the oil burner side near the top say? And a picture of the actual model number plate too

EBEBRATT-Ed

@Nativebostonian97

That boiler I believe is a early 1970s Dunkirk or Pennaco. HB Smith bought those boilers and put their name on them. They were pretty decent boilers

Steamhead

These were also branded Utica and Columbia. They were built like tanks- ask anyone who has had to replace one.

PC7060

If you are going to convert to hot water you’d be better off replacing entire system with a condensing boiler and new emitters (eg panel rads) properly sized for low temperature (120F SWT max).  This assumes as Jamie said earlier, you seal and insulate the envelope. 

Much more costly than just replacing the steam boiler and keeping current radiators and piping.  Only you can make the call if it’s worth the investment. 

STvex

Does your boiler work and are you getting heat? If yes, then why change. Now isn't a good time to buy a boiler, prices are still high.

Waher

@Nativebostonian97 Don't go making foolish changes to your system based on chasing relatively trivial rebates from MassSave program.

A well functioning and insulated one pipe steam system is equally efficient to a forced hot water system regardless of whatever a flake engineer that's not familiar with steam will tell you.

I would replace your boiler (& near boiler piping) with a new appropriated sized gas fired connected to a new stainless chimney liner, replace and add additional venting to your steam mains, get your steam mains and risers properly insulated, and go with an indirect water heater.

Let an experienced steam fitter (which is not 99% of the plumbing/HVAC companies around the Boston Metro area anymore no matter what they tell you) review your system before changing anything.

gmcinnes

@Steamhead Replacing mine involved a sledgehammer, an electric hand truck, and a goddawful oily, sooty mess

HVACNUT

That's a Dunkirk 1352. It was badged under many names, including Sears.
If you want to switch to gas, fine, but keep the steam. It seems like a huge upfront cost (with your labor presumably) with very little return. Fewer and much less expensive replacement parts as well.
If you stick with steam and are going to tackle it yourself, read the manual first because the existing near boiler piping is not correct. And if you have steam questions, this is where you'll get the correct answers. Not from me, but from actual steam pro's. 

It also looks like an ABC Sunray 1725 low speed burner with a 3450 PSC motor. 

Steamhead

HVACNUT said:

......It also looks like an ABC Sunray 1725 low speed burner with a 3450 PSC motor. 

Actually that's the Sunray FC Bantam which was 3450-RPM. My Burnham V-14 originally came with one. They were as good as any other flame-retention burner if you set them up right.

EBEBRATT-Ed

@Steamhead

My sort of brother in law still has one....steam with the original Beckett AF probably around 1970. There was a Texaco distributor in Boston "Union Oil" that sold oil (I was working for an oil co back then). They had a whole line of equipment that they rebranded and painted some of it red and put the Texaco Logo on them including the Becket AF. You could buy the burners for about $20.00 cheaper than at the local supply house if you didn't mind the Texaco red paint. The AF was about $200 with a cad cell control at a supply house.

They also sold a rebranded Texaco burner that was a slow speed Ducane burner that was actually pretty

decent for what it was.....$75.00 if you stuck with the stack switch. People were cheap back then and before the embargo oil was $.25-$.30/gallon so people didn't care and you couldn't even sell a burner unless the old one burned up an air tube or something. All the burners I worked on were old "Petro" burners installed in the 20s, 30s &40s In the early days a lot of people didn't like the "noisy" AF. A lot of the old coal boilers had chambers made of "hard" fire brick which made the AF noisy. If you put a liner in the chamber or replaced it with soft fire brick it was a lot quieter.