Steam to Hot Water Conversion

Garret

Interesting... I'm digging through my notes now, and I don't know how I got the $1.17/therm figure. Just looking at the last few power bills, it has varied from $0.96-1.07.

Oh, now I see, I was including the delivery charge. My December bill says delivery charge: $0.1336/therm, gas charge: $1.0796/therm. So a total of $1.21/therm.

Regarding electric heat, I'd consider it, but I don't know how it would work. I don't have any duct work right now (we might get an a/c microduct system some day, but that's a long way off -- window units are fine for now).

How does electric heat interface with a system of steam rads? I don't want to add electric baseboard or anything like that.

I think Illinois electric rates have been artificially low for a year or so, because of some rate reduction settlement. Not sure of the details on that, but I had noticed that our summer electric (a/c bill) was pretty reasonable.

I hadn't heard of that special "Space Heating Plan". That's a very good deal, if it's for real... I'll give Ameren a call and see what they say.

Heat pump, huh... I'm completely clueless about that stuff... gotta do some more reading.

Best,
-Garret

Rich_31

Steam to Hot Water Conversion

I have a 2600 sq. ft. home (heated area 1st and 2nd floor excluding basement)with a two pipe steam system. The boiler is an American Standard 375000 BTU input and 300000 BTU output and I=B=R of 938 sq ft. steam that is at least 30 years old.

A connected load calculation says I have 115000 BTU (645 sq ft.steam)of connected radiation (includes 1.33 pipe pick-up), which is in the form of copper tube convectors with aluminum fins that are recessed into the exterior walls of each room.

A heat loss calculation says I need 90000 BTU.

I would like to convert to hot water using a Weil-McLain Ultra (or similar high condensing system with outdoor reset) to get a high effiency system, but I don't know if it will work in my house using the present steam piping and heat convectors.

The things that concern me are that some of the return piping is only 1/2 inch pipe and the steam traps have even have further restriction.

I'm afraid that if I run the system at a high temperature like 210 F that the efficiency will drop.

The whole purpose is to reduce my heating costs which now run about $3000 per year using natural gas.

Should I expect to be able to save money by doing the conversion? Would it be better to keep the steam system and improve on it somehow?

If anyone that has experience doing a steam to hot water conversion could provide comment, I would appreciate it.

I live in Pittsburgh, PA.

Thanks

Brad White_56

Unless you are willing to significantly increase your radiation

I would keep it as steam.

Yes you may have a current surplus of radiation but you are barely in the range of converting to hot water running at 165 degrees average and having it still work. (e.g.: 175 supply, 155 return).

To get the best benefit out of a condensing boiler, I would want to see your 90,000 heat loss met by radiation sized at 140 average water temperature or lower. Either lower the heat loss to meet the existing radiation or add radiation to meet the heat loss with cooler water.

For the effort you are about to undertake, I would keep it steam.

What might change my mind (given the boiler is going to be changed out anyway) is if the house would be or was insulated and could bring that 90,000 heat loss down to the range of 60,000 BTU's per hour. That would be in my opinion an minimally ideal ratio of radiation to heat loss. You could heat your house on the coldest day of the year with 150 degree water, more or less. For much more cost you could add radiation until it totals about 1,000 SF EDR and get the same end result.

If your 90 MBH heat loss is as good as it gets, I would stick to steam and improve it to it's best efficiency.

My $0.02

Brad

Steamhead (in transit)

You could be inviting trouble

go here for more:

http://www.heatinghelp.com/newsletter.cfm?Id=22

Then there are the reliability issues we've seen with the Ultra and other modulating/condensing boilers.

If your system is two-pipe, it's probably Vapor. Vapor was the Cadillac of heating in its day and is still one of the best out there. With this type of system you can often gain efficiency by just getting the basics right. How about posting some pics of the boiler area and a few radiators?

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jalcoplumb_2

Wow!!

"copper tube convectors with aluminum fins that are recessed into the exterior walls of each room."

I have seen this done before. Chances are you nothing but the sheating and siding behind that unit. Heat goes right out of the house. Is there any insulation between the unit and the outside wall? Your heating bill could be so high due to the fact you are heating the neighborhood.

Did you have any manufactures information on the convectors? Brand? How did you figure the convector heat output?

Do your mains have any insulation? What is the condition of your house envelope? Do you have insulation or updated windows?

1/2" pipe can carry around 15,000 btu's so as long as your convector output is less that should not be a big issue. As for the traps if you convert the guts can be removed, or radiator elbows can be added.

The pictures requested can help.

Lot of factors to consider.

Unknown

ahhh Pittsburgh

Too bad if u had posted earlier, I have friends in Pittsburgh and was there twice late last nov/dec... I'm a hockey fan..
Regarding ur project, I've done many steam to hot water converison jobs without any plms as I need to see all the troublespots as the prevoius wallies pointed out... Any pictures will help to "see" what we will tackle... Be "talkin" more soon..

Rich_31

Steam to Hot Water Conversion

Thank you Brad White, Steamhead, Jalcoplumb, and rjbphd
for your input to my post. I have attached some pictures of the heat convectors and steam boiler that is im my house.

I got the radiation numbers from OCS Industries on the web because their convectors look very similar to mine. Also, I recalculted my to radiated load to be 125000 BTU or 520 sq. ft.

I now realize that I can't get the heat out of the convectors that I need using hot water even if I take the temperature all the way up to 200 degrees. And even if I could get it to work at that temperature I don't think the boiler would ever condense, so there goes my savings over steam. As much as I'd like to go with a high efficiency water system, I don't think I'd ever get the cost of conversion back if I have to add/change my piping and radiation.

I'd appreciate your comments on this.

Also, if I stay with steam and try to improve my efficiency, do you think it would be cost effective to install a new steam boiler? What do you think a new boiler like a Burnham Independence 7 or Weil-McClain EG-55 at around 125 or 130 MBH would cost to have installed to replace my current boiler.

I do intend to further insulate my walls from the inside, but I also want to have the most effiecient heating system as resonable (meaning cost effective) as possible.

Thanks for your help.

Rich

Garret

First off, yay Pittsburgh. I grew up in the South Hills (Mt. Lebanon), and I'm still a big pens and stillers fan.

I'm just a homeowner, going through the same math you are. And I thought my system was inefficient, given its age and that we've been hit with a few $400/month gas bills of late.

But what you're describing is something else.... I'm in Champaign, Illinois, which has almost exactly the same climate as Pittsburgh for heating degree days. (Check Weather Undergound for HDD data).

The heated area of my house is 1800 sq feet. That doesn't count the unheated basement.. just the first and second floors.

My boiler is from 1923, and was converted over to gas a long time ago.. the current conversion burner is probably 30-40 years old. I have a two-pipe system with cast iron standing radiators (not convectors).

This last heating season (not the full year, just Nov - March), I used 747 therms. That's heating only... I subtracted out the baseline gas usage from summer months (stove/dryer/water heater).

So ignoring all questions about heat output efficiency, let's just look at the input side..

I burned 747 therms in Nov - Mar, which was 4607 HDD.
That's 747*100,000 / 4607 = 16,214 Btu/HDD.

I don't know what your gas cost is... mine is around $1.17 per therm. If yours was considerably different, we'll have to adjust this math.

At $3000 a year, you're burning about 2564 therms. Since you gave a full year cost, let's go ahead and use the average year's HDD for Pittsburgh, 5733.

2564 * 100,000 / 5733 = 44,724 Btu/HDD.

Now, your house is bigger than mine. So let's compare Btu/HDD/sq foot...

Mine: 16,214 / 1800 = 9 Btu/HDD/sq foot
Yours: 44,724 / 2600 = 17 Btu/HDD/sq foot

Yikes!

First off, you have a huge boiler. Mine is burning 150,000 btu/hour right now. I have no idea what the output is, but I doubt it's more than 90,000 btu/hour. So if/when you do replace the boiler, I'd seriously look at reducing the size.

Here's another question... Do you use a setback thermostat? Is the house occupied during the work week day?

We keep a very deep setback. The boiler basically shuts off at 11 pm, and only comes up to 64 degrees during the day when we're at work. When we're home and awake, it's set to 68. We have a honeywell programmable smart recovery thermostat, which work very well.. I can't remember the last time I caught it playing catch-up or overshooting.

I'm afraid though that "jalcoplum" nailed it above.. those "in wall" convectors could be the problem... Unless your house is extremely well insulated, you're basically dumping heat out the wall, and keeping very little of it. I know my boiler is old and inefficient, but at least I know that any heat that makes it into a radiator will make it into the living space.

Maybe some of the dead men weren't as smart as some of the other dead men.

What are you windows like? Last year we replaced our upstairs windows with marvin inserts... looks great and the air infiltration is way down. We'll do the downstairs one of these years if we can get the funds together.

-Garret

Steamhead (in transit)

That's a Vapor system

have you found any names on the traps or convectors? And where exactly are the traps located- I can't see them in the pics. Did they put them under the floor?

Are there any Vapor devices in the return piping around the boiler?

Speaking of the boiler- those old American-Standards often had combustion efficiencies below 80% or so. Have someone run a digital analysis to be sure. That and the fact that it's oversized would make replacement an attractive proposition.

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Mike E_2

I was recently visiting some friends that now live in Champaign. They have an apt up near the Market Place Mall. I asked them what the utility costs were down there, and they got out a bill. Their apt is all electric, so there is no gas cost on the bill, but the electric rate is $0.02499/kwh for space heating use, $0.0707 for the first 300KWH and then $0.0594 after that.

If your gas cost is $1.17/therm, it would be way cheaper for you to use electric heat. Gas would have to be less than $0.73/therm for it to be cheaper than resistance heat. And if you had a heat pump put in, gas would have to be cheaper than $0.27!

Here's a link to Ameren's residential rate schedule.
https://www2.ameren.com/ACMSContent/Rates/Rates_ipel13rtSC2.pdf

It appears that any residential house qualifies for this rate, so I was just curious as to why you're using gas.

Michael

Rich Shehab

Steam to Hot Water Conversion

Garret:

Thanks for your reply.

My heating bills for November through March for this heating season totaled 155 MCF of gas. (I'm paying $14.56/MCF for the record) My gas usage over the years show that I use about 4 cfm per month for hot water and gas dryer. Therefore my steam boiler used 135 CFM from November to March. To convert to Therms: 135000 /96.7 = 1396 Therms.

Therefore:

Yours: 747*100,000 / 4607 = 16,214 Btu/HDD

Yours: 16,214 / 1800 = 9 Btu/HDD/sq foot

Mine: 1396*100,000 / 5733 = 24350 Btu/HDD

Mine: 24350 / 2600 = 9.36 Btu/HDD/sq foot

My gas usage per HDD/sq foot is almost exactly the same as yours! That's pretty amazing. So it looks like we have about the same effiency heating systems.

What I plan to do now is continue to inslulate my house as well as replace all the intenals of the traps on the convectors and insulate the steam pipes. I plan to stay with steam heat and replace the steam boiler with a new one with about 125 or 130 I=B=R steam rating.

I've already replaced all the windows with Low E argon filled.

This website has been a tremendous help in figuring out what the best approach is for improving my heating system.

I'd still like to get an idea what a new boiler should cost to have installed, so if anybody out there can give me an idea, it would be appreciated.

By the way, I live in Mt. Lebonan. I'll drop you a note to your email address.

Best Regards:

Rich

jalcoplumb_2

Heat loss based on convectors?

Did you determine the heat-loss of the house structure using a heat-loss program or are you adding up all your convector outputs and comming up with it?

From the pictures it looks like the convector recess is right to the outside wall.

If it were me I would insulate and close the recess. Do an accurate heat-loss calculation room by room. Figure out how much baseboard heat for each room based on the heat-loss. If each room is under 15,000 btu I woud run 1/2" Pex Feed and returns back to a radiant manifold back at the boiler. In most cases 1/2" pex can be fished to the second floor like a wire with min. damage to walls and ceilings. A lot of old housed around here were ballon framed.

This will cost more in the long run, but with gas cost on the rise you will get a payback. You will also improve the envelope of your structure and not heat as much of the neighborhood.

Realize that when you calculate the payback with today's gas cost you are not being accurate. You can't assume the gas cost is a constant. When you add in the rise in gas cost you will realize a quicker payback.

Garret

correction to your math

I think I noticed a little problem... the HDD value I had given for Pittsburgh (5733) was for a full year, not just Nov - March.

For this most recent heating season, Pittsburgh's Nov - March HDD was 4293.

So adjusting the math...

My Champaign house:
747*100,000 / 4607 = 16,214 Btu/HDD
16,214 / 1800 = 9 Btu/HDD/sq foot

Your Pittsburgh house:
1396*100,000 / 4293 = 32,518 Btu/HDD
32,518 / 2600 = 12.5 Btu/HDD/sq foot

Did you ever find the air vents on your system? I can't seem em in the photos you provides. They should be somewhere, over the boiler, on the ends of the mains, and on the return piping. Mine look(ed) something like this:

http://www.worksongs.net/photos/2006-02-Boiler-Replacement/slides/SBG_7858.html

http://www.worksongs.net/photos/2006-02-Boiler-Replacement/slides/SBG_7868.html

One really important thing I learned from this site and Dan's books, is that venting is absolutely critical to a steam system... and if the venting on an older system hasn't been improved since the coal days, it's likely to be insufficient. I've replaced all my vents with Gorton #2s, and the system gets heat to the radiators much faster now.

-Garret