OWB Boiler to retrofit an old steam system

[Bigus Termitius]

Has anyone converted an old steam system to run off of an owb boiler?

The only info I get so far is for commercial applications. Maybe I haven't searched hard enough, but thought maybe this forum might have some answers. I'm moving into an old house with steam heat this winter and I'm looking into a owb system to replace the propane system and hot water heater if possible. Might not get it done this year, but would like to have a plan in place for it. I might run the shop off of one to.

I'm still really new to the tech so any advice is well appreciated.

 

[fdoberman]

Steam is a very expensive way to heat a house or any small situation.

If you're asking if the steam system can be converted to a hot water system, the answer is generally maybe.

If the house is equipped with cast iron radiators, and a 2 pipe system chances are good it can be switched over tohot water by getting the steam traps out of the system and eliminating radiator bypasses if they are in the system.

Cast radiators & hot water yield excellent efficiency in heating.

 

[mikenc]

Haven't converted to OWB but the principal will be the same for commercial or residential. Do you have baseboard, radiators or steam coil in ahu unit with duct work?

 

[Bigus Termitius]

No duct work. House was built in the late 1800's. It's a steam system with the cast iron radiators. Haven't checked the plumbing, but I've been reading about going to the hotwater system from steam. I'll be over there today working so I'll check for sure.

If it's steam and hard to convert to hotwater, I can live with the inefficencies if I can run it off a owb and plumb in the hot water heater.

 

[Oxford]

Good afternoon,

As a previous poster mentioned, you can convert your steam system to hot water by removing the steam traps and getting rid of any radiator bypasses.

What you won't have in most cases is thermostatic zone control in terms of a wall thermostat controlling a zone valve or pump. Most old steam systems have a throttling valve on the radiator, meaning that you are the thermostat. Works OK, but not automatic and people underestimate how much they like thermostats.

What you can't do is create steam with an OWB, because to my knowledge none of them are pressure vessels, and unless you can create pressure you can't create steam. Pressure vessels for boilers require an ASME stamp, which ain't cheap and would put the days of the $3k boiler in the extinct list.

A word of caution about the conversion: because OWBs are open to the atmosphere, the water circulating in them is oxygen rich, meaning that it is very corrosive especially to iron pipe or steel, which is why so many complaints about them start something like "I've got pinholes in my piping/heat exchanger/welds..." If you open a steam system and put OWB hot water through it, expect leaks. You would be wise to put a water to water heat exchanger in the system and keep your home's existing heat piping in a pressurized, closed system IMO.

By the way, is WWHP still in Farmer City? You must be around there somewhere. It's a great station, or was.

Oxford

 

[fdoberman]

Given the build date chances are pretty good the original system was probably a coal fired constant heat boiler.

Unless it is a 1 pipe system the conversion is fairly straight forward.

First the steam traps to individual radiators need to be eliminated.
Steam traps operate in a similar fashion to expansion valves on AC units. With the traps in place no water flow will occurr through the radiator.

Second, if the individual radiators have bypasses they too need to be removed and blocked off. Since water flow takes the path of least resistance a bypass will leave you with a cold radiator.

 

[Bigus Termitius]

Good afternoon,

As a previous poster mentioned, you can convert your steam system to hot water by removing the steam traps and getting rid of any radiator bypasses.

What you won't have in most cases is thermostatic zone control in terms of a wall thermostat controlling a zone valve or pump. Most old steam systems have a throttling valve on the radiator, meaning that you are the thermostat. Works OK, but not automatic and people underestimate how much they like thermostats.

What you can't do is create steam with an OWB, because to my knowledge none of them are pressure vessels, and unless you can create pressure you can't create steam. Pressure vessels for boilers require an ASME stamp, which ain't cheap and would put the days of the $3k boiler in the extinct list.

A word of caution about the conversion: because OWBs are open to the atmosphere, the water circulating in them is oxygen rich, meaning that it is very corrosive especially to iron pipe or steel, which is why so many complaints about them start something like "I've got pinholes in my piping/heat exchanger/welds..." If you open a steam system and put OWB hot water through it, expect leaks. You would be wise to put a water to water heat exchanger in the system and keep your home's existing heat piping in a pressurized, closed system IMO.

By the way, is WWHP still in Farmer City? You must be around there somewhere. It's a great station, or was.

Oxford

Thanks for the information. Excellent point about the oxygen rich water. Never heard of a water to water exchanger, but that sound interesting.

Yep. The whip is still around. Farmer City is my hometown btw. Don't get there too often though, I'm about 40 minutes northeast in rural Gibson City. I like it alot better up this way and the whip still comes in real good. I think you can get in online now. The Whip Radio Station - Somewhere between Memphis & Chicago

 

[leon]

owb conversion

Has anyone converted an old steam system to run off of an owb boiler?

The only info I get so far is for commercial applications.
Maybe I haven't searched hard enough, but thought maybe this forum
might have some answers.

I'm moving into an old house with steam heat this winter and I'm looking
into a owb system to replace the propane system and hot water heater if possible.

I Might not get it done this year, but would like to have a plan in place for it.

I might run the shop off of one to.

I'm still really new to the tech so any advice is well appreciated.

Hello Bigus Terminitius,


If the steam radiator has a single pipe system its will
cost you more to do it than buying a Harman wood and
coal boiler and adding it in parallel with the other steam
boiler that you have.


A single pipe steam system is the best type of steam
heating system no matter what anyone says as it is the
simplest way to heat a home or shop.

The steam radiator also loses heat nuch, much, much slower
than a hot water system as every inch of baseboard loses
the heat and returns much colder water to the heating appliance.


The amount of water needed to make steam is miniscule compared
to the requirements of a hot water recirculating boiler.


You can use your steam boiler to make domestic hot water but
you need hot water coil in the boiler which is something harman
offers in its wood and coal boilers which are steam certified.


You need a blending valve/scalding prevention valve at the water
heater which is required by code now for all water faucets.


You do not want any other heating method than the steam
you already have as it delivers the most heat energy for a
home.


And the heat comes with the least amount of fuel burned
per gallon of water as the low pressure steam is huge source
of heat energy for a home.


I absolutely hate my hot water heating system and I
wish I had steam instead as the hot water baseboard
radiators are heat wasters in old homes.


This comes from the experience of dealing 33 years of
heating and dealing with poorly insulated old home with
wood and coal.


A hot water system loses its heat faster that a steam system
does because the working high temperature is lower in Degrees Fahrenheit.


A steam system only works when the system is calling for heat and you will
burn much less wood and coal than using a water stove which will require a
very large amount of wood to keep the heat flowing where a steam system
is only reheating a small amount of water to make heated steam to heat a home.


You will lose a tremendous amount heat energy in smoke from the water stoves
simply idling when the home is not calling for heat as well.


I burn more wood and coal now with a hot water baseboard system than
I would with a low pressure steam system.

 

[woodman6666]

I agree with previous posts get everything out of the line so water only goes straight through the radiators and nothing else. A good way to do the control is a simple 2 zone valve when house is cold water flows through all radiators and when house is satisfied it bypasses the home and just hits the domestic hot water heater and returns to the owb. I have done this before and worked fine.

Firewood Rochester, Winona, St. Paul, MN - ProCut Firewood

 

[fdoberman]

can explain how fuel is saved when it takes a whole wheelbarrow of BTUs from 212° water to steam.

Steam only becomes efficient in large systems. We build some pretty large school buildings around here with hot water heat because it is more efficient and has less problems than steam.

I'd be interested in your expanding on your theory of hot water hydronic systems loosing heat in old buildings as well. A hydronic system piped with copper has very low BTU loss until the fluid enters the radiation unit where the aluminum fins transfer the heat to the air in the room. Copper itself has terrible heat transfer characteristics giving heat off to surrounding air.

The only problem I forsee in the proposed conversion of an old system to cast iron hydronic will be if the structure is multiple story, and radiation is above the OWB. In that case either the boiler system will need to be closed, or a pump other than a normal hydronic circulator will need to be employed in the setup.

In my opinion domestic hot water is best made by installing a water to water transfer inside of the house with a hot water holding tank. It is a bit more expensive initially, but the cost is worth it over time.

 

[Bigus Termitius]

It is, in fact, a one pipe steam system. I checked on that this evening when we were there making preparations to move in. It is doubtful that I will be able to switch it to hot water at this point. This water to water exchanger seems to be a viable option as well as any outdoor boiler that could power the steam system. It is a two story home, btw.

 

[leon]

heat etc.

The funny thing about steam heat is the FACT that a very
small amount of water and a heat source is used to create heat
and the cooled condensate is dripping back to the boiler when the
low pressure steam cools.


Heat always conducts itself to any cold surface and poorly insulated homes
and single pane windows also lose heat.

A baseboard single loop heats areas that are unoccupied and require the
baffles to be shut when they are unoccupied to conserve the heat in the water.

There is no reason he could not wrap his steam pipes with fiberglass
insulation ment for steam heating which will save a lot of heat energy
for a steam system


A water stove will use much more water and much more wood and
lose much more heat energy just in the design of the water stove
as has been mentioned before where idling permits huge amounts
of smoke containing useable heat energy which is lost forever once
it exits the stack.


This is why the water stoves are so inefficient, if they had a huge mass
of water in a well insulated shell with a firebox that was half filled with standard
fire brick used to capture heat and release heat back into the combustion
chamber as a thermal mass when burning and using a simple water heat
exchanger scrubber to remove the particulates and take back a portion of
the heat they would be better but I do not see that happening in any case
because it would cost more to make a better water stove that pollutes much less.

My boiler is half filled with standard firebrick and I wish I had done this 29 years
ago as I use much less wood and coal.

My inlaws home was Montgomery Wards kit home that was
heated with a coal fired steam boiler and I believe that they had a
domestic coil in the old boiler until the area was serviced with
natural gas and they converted to a gas hot water heater.


A hot water hydronic heating system costs the plumber less to
install as it takes less time and the mark up is greater as the
parts cost less why do we not get that out of the way first?, AS you do not require
Schedule 80 piping for a hot water baseboard system.


The other thing you have not mentioned is that some insurers
frown on steam heating for school premises or residences as
they consider it greater liability.


In my inlaws case the steam boiler was very, very. very, small.
and it was plumbed with a single pipe system.

The steam boiler we used to heat the apartment we lived in over
my parents business was the size of a small roll around tool box
which fed several single pipe steam radiators in the apartment.


A typical home using low pressure steam for heating is 15P.S.I.G.,
as long as the radiators are in good condition, steam vents, and shut off
valves are in working order and the boiler water levels is maintained
steam is much easier to deal with and still heats very well and the
heat is a very even productive conductive heat passing through the radiator
sections which conduct the low pressure steam into the interior of the
individual radiator with the thermostat regulators allowing the individual
radiator to vent to increase the heat if desired or simply controlling the heat
load with a thermostat for the entire home.



There is no reason he could not a run a steam line to the shop he intends to heat
as well either.


As he has mentioned the system is a single pipe system and its simply a matter of
adding the temperature regulators to the radiators to control the temperatures and save
money and wood or coal if the radiators do not have them.


The cost for converting a steam system that works well to hot water is not money
well spent and could be used somewhere else as the maintenance is minimal AS LONG
as the water is treated or flushed and the pipes are inspected and shut off valves are replaced
during the off season to prevent problems during the heating season.


You will be adding pumps which will run and run and run and simply add to the expense
when a pump is not required for a small home steam system.


Adding a Harman boiler WHICH is steam tested A.S.M.E. rating will save you more money and cost less than any water stove as the water stove will not be able to make hot water hot enough to utilise it to make steam in the propane boiler as a limited amount of water is used in the steam chamber to make steam.

Hiring a reliable plumber that repairs and maintains steam systems is simply a plus for the
home owner as many steam systems are very old and very reliable still so..............

 

[fdoberman]

Leon, you threw everything in there except the kitchen sink and a log splitter, and you refused to deal with the additional BTUs requierd to convert 1 pound of water to 1 pound of steam. I'll not even mention the BTU input to get from normal 180° water to steam.

When you hurl in the circulator pump consuming electrons at great cost you've gotten way past ridiculous.

The OP didn't ask about single pane windows or drafty houses, he asked IF the present system could be converted to hot water with an OWB acting as the heat source.

Getting back to the original question, and considering we now know it to be a 1 pipe steam system, in a multistory building my answer now becomes it is doable only by replumbing the radiators. Fortunately there is PEX. The OWB will also have to be a closed boiler system rather than vented to get fluid to the second floor, and probably 2 expansion tanks will need to be added.