stay with gravity?

Bernie Riddle

I have owned an 1880's Victorian for almost 3 years. The heat is provided by a gravity boiler with CI radiation. The tag on the boiler shows it to be a Janitrol Gas Boiler, size 7-33 with a serial # of 3554. It also shows an AGA rating of 1080 sq. ft. steam and 1730 sq ft water with a rated input of 324,000 BTU/HR and vented with a 9" single wall into a 25' brick chimney. The boiler is located in the 200 sq ft basement at the back of the house and can make the house as hot as we can stand. Having read Dan's article in the Blog on boiler sizing I would say all the rules he cited have been used in this case.My concern is our ever growing nat. gas bill. HW is provided with a separate gas WH.We have had maintaince performed but there are very few (if any ) future Dead Men in our area.(western West Virginia on the Ohio River). I have been reading this site and I think you guys can help with my decision.
In looking at new more efficient boilers than my current antique I am leaning toward a peerless mi-5 because it has the same supply and return fittngs. I have done a couple of the HL calcs available on the net and calculated out at 140,000 btu. By using this boiler I could stay with the current gravity feed set up which must have been designed by someone very knowledgable because we have no flow problems or noise in the system. Following the rule if it ain't broke don't fix it I am leaning to stay with the gravity system. any suggestions are welcomed and needed. Thanks guys

Firedragon_4

I would and

have, if it isn't broken, you CAN'T fix it, but you can sure screw it up by trying.

Floyd_7

Not me....

betchya the radiantion is oversized also......
IF, installed right a condensing boiler with a pump would probably be heating ya up with water temps in the 120's most of the winter......
My house with all it's CI is heating just fine @ 38 outside and 120 for water temp. 80 year old brick house with NO insulation ANYWHERE!!!!!!
You could be getting very high 90's eff. out of your ever rising price of gas.....

Floyd

.

Gravity went out of fashion because circulators gave faster response and you could do quick response start/stop heating, thus allowing precise on/off control of heat with themostats, setback, and all those things.

Now gravity is the cutting edge of fashion, because continuous circulation is "in" and people are beginning to realize that pumps consume power and no one factors this in when telling you how much money you'll save with a new boiler. Some boilers need P/S piping and multiple pumps...but gravity IS constant circulation, from before anyone knew that term, and with no need for pumps running 24/7.

Updates to Victorians should be sensitive to the period. Nothing at all wrong with gravity heat if it works for you.

You shouldn't buy a boiler based on fittings, though. Better to hire someone who can do plumbing.

Bernie Riddle

The reasoning behind looking at matching fittings on the boiler is to maintain the good service that the plumbing already installed is providing. The current boiler has two sets of supply and returns. One set is 3"s and the other is 2". The system currently works great as far as plumbing but I had one NG bill (monthly) last year of almost $800.00. I think thats a bit much for a 3600 sq ft house.

Betz

I'm in the same area, almost same size house

Hi Bernie, I'm in southeastern ohio and had a similar system, although long ago it was converted to a forced circulation system. I couldn't afford the gas bills I was having from my circa 1906 coal coverted to gas boiler, so I installed an outdoor wood furnace. Now my bills are $0. It also has a gas backup with a 150,000 btu burner that is around 85% efficient (or so). If you want an option like this I can show you a few things I've done to tie it into my existing system. I can say that one thing that will help your efficiency is to insulate all those huge pipes, something I plan to do very soon. Anyway, good luck on your system and your bills, I know exactly what you're feeling in that regard.

Constantin

Sounds like several issues at once...

I am going to go out on a limb and expect your home to be as uninsulated as I found mine to be. Insulation and weatherization makes a huge difference, it can cut your heating costs in half. Consider getting modern storm windows like Harvey Tru-Channel units, that allow you to reduce infiltration via the window sashes while maintaining the wavy glass on the inside.

Insulation in the walls can be retrofit quite nicely, even with the clap-board and interior walls in place. They simply drill two holes in each stud bay and fill 'er up with either open-cell foam (Icynene, et. al) or dense-pack cellulose. Either way, you get R3.7/inch in the walls and a much tighter envelope.

As for the gravity system, I wouldn't change anything drastically until you have consulted with someone knowledgable about how to convert it to a modern boiler. Several folks on the wall have posted success stories and the likely abundance of radiators in your house should allow a conensing, modulating gas boiler like the Munchkin, Trinity, Ultra, or Vitodens to run at peak efficiency most, if not all of the time. Plus, they'll make you plenty of potable hot water via a IDWH.

IIRC, Mike T rebuilt his gravity system to accept TRVs on all the radiators and hence has an infinitely proportinal heating system. Dead simple, very efficient, and bulletproof. So not only can it be done, it has been done. Just find the right contractor, not someone who'se first instinct it is to rip out all the "Dead Men's" work and replace it with copper piping.

As for the gas bill, that seems very high. In Boston where I live, we spent about as much for a month of oil at current oil prices when the house was gutted, open during the day (i.e. windows out, etc.), and it wasn't particularly warm either. Thus, I would address the insulation/weatherization of the home first, the heating system second, because the better the system matches the house, the more money you will save.

Mike T., Swampeast MO

If you're willing to lay out some $$ to turn a once first-class system into a truly modern first-class system of exceptional comfort and fuel efficiency, install Thermostatic Radiator Valves on all of the radiators and use a Viessmann Vitodens boiler.

Expect 50% or greater reduction in fuel consumption--seriously. Expect comfort that rivals radiant floors with response nearly as fast as forced air--honestly. There are less expensive options when it comes to the boiler, but the Vitodens can likely be installed with the least modification to the piping.

The TRVs and Vitodens combined on a gravity system VERY closely emulate the gravity circulation during maintenance while still giving the benefits of forced circulation.

Ken_8

I would strongly urge you...

to keep the gravity system and simply use something to emulate the vertical "stacking" means used to create flow now.

Perhaps a Super Store as that "vertical flow inducer" tied to an extremely efficient condensing boiler.

Domestic hot water would also be derived from the same boiler and perhaps another Super Store indirect?

That would be the best of both worlds IMO

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bernie_3

You are right about the insulation. I have insulated the attic with 6" blow-in. The floored attic(unheated) would only allow that much. The side walls are of ballon frame construction and are open at the bottom. I've done a lot of crawling around in the 24" crawl space and I can't come up with a good way to seal those bays at the bottom so that I can blow in the insulation.The windows all have 3track storms and we have pulled all the wood sashes and re-fit them. I don't know if new storms would gain me a lot.

Ken_8

This too would work extremely well but...

Could be improved upon with zoning and day/night thermostat strategies.

However, once you go to these extremes the entire beauty of the existing and perfectly functioning system would be aborted and the $$$ would go through the roof!

If it's gravity and workes perfectly and the gas consumption is THE only problem; address the problem (the boiler - period) not the world.

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bernie_3

I live in a designated historic district and I'm pretty sure I could not get approval for an outdoor boiler.

bernie_3

Ken, Thats the conclusion I had come to in reading all of the good words on this site for a couple of months.I had looked at a lot of boilers but the only one I could find that gave me the closest fit-up to what I currently have is the Peerless 61-5. I had mentioned the MI-5 in my first post but that was in error. I am trying to follow the KISS rule.(KEEP IT SIMPLE STUPID!) I resemble that remark. BTW thanks for all the replys. What a great resource for us homeowners!

Mike T., Swampeast MO

TRVs Provide Complete and Total \"Zoning\"

Each radiator becomes its own "zone" but ALL interact into the system without any piping changes save the valves and a differential pressure bypass. The entire structure becomes a single proportional "zone" made up of any number of individual proportional "zones".

All sorts of setback options (manual and automatic)--not counting the built-in ability of the boiler.

bernie_3

I install a Honeywell setback t-stat last year. It seems to work fine as far as keeping the home at the temps we wnat when we want. I also had a simple outdoor temp reset installed two years ago. At 45* outdoor temp it takes boiler temp to 100*. I'm not sure what my NG bill would have been without those.

Uni R

Gravity hybrid

Bernie, I would be curious about exploring a hybrid P/S gravity system. The housing loop would remain a large gravity loop but piped to that be a condensing boiler in the same manner as W-M recommends for their Ultra (I.E. the closely spaced tees would be for the boiler loop off of the heating loop). You'd keep the constant circulation that the dead men gave you and be heating it with a modern modulating boiler which should only make it even better.

Steve Rockwell_3

I'm with Constantin

I also have an old house, a 1920's Tudor Revival located in West Michigan. Gas bills when we moved in 4 years ago were $500+ per month in the winter, with nasty ice dams, and a gentle wind blowing through the living room due to air infiltration. I hate to think what the gas bills would be today had we not made some upgrades.

Our house had some insulation, if you can call it that - about 1/2" of horse hair. Surely the state of the art in 1925. Fine Homebuilding magazine has had several articles on energy efficiency that helped me learn the issues and develop a plan. They have combined them in a couple of books, "Energy Efficient Building" and "Build Like A Pro - Insulate and Weatherize." Buy them through Amazon or Taunton.com before you do anything.

I had an energy audit done on the house, which included a blower door test. The state reimbursed us $300 of the $350 cost. We were awarded the dubious distinction of being the leakiest house he had ever tested. After air sealing the house, then using both dense pack cellulose and Icynene insulation, our gas usage dropped roughly 40%. Less heat lost also allowed us to use a smaller boiler.

The next step was lurking on "The Wall" and learning about the options for equipment replacement. Our house is a mix of copper fin baseboard and standing cast iron radiators. We installed a Weil-Mclain Ultra condensing boiler a month ago (with about 40% of the output of the old boiler), on constant circulation, and have been thrilled with the results. The remaining air infiltration is gone, due in my opinion to the boiler's sealed combustion. The new boiler takes cumbustion air directly from outdoors, rather than stealing air from inside the house I've already paid to heat. No indoor breezes, no hot or cold spots. Gas usage is yet to be confirmed, but I can no longer hear the gas meter spinning around from one floor above (not kidding) so it has to be an improvement. Gas usage vs. last year did drop 36% on the first bill, which included only 2 weeks with the new boiler. Who knows if the weather was comparable.

As for the cast iron, I have found our cast iron rads, which now all have TRV's, to be even more comfortable than the baseboards. I can't give you the reason why. I wouldn't consider ripping out the rads and replacing with baseboard. Weatherize the house, swap out the boiler with an Ultra, Vitodens, Munchkin/Peerless, or the new Buderus condenser, install an indirect dhw heater, and put a smile on your face.

Not only will you enjoy improved comfort (which I doubted, but it's absulutely true), but you may find your gas bills will be a fraction of what they are today.

Mike T., Swampeast MO

Are your old mains sized down at the current boiler--and it's still operating well under gravity circulation and with full outdoor reset??? Am guessing that the supply temp sensor for the reset control is strapped on to one of the supply pipes?

Looks like that Peerless MI-05 holds 7.28 gallons with 1½" supply tapping and 1¼" return tapping. The old Janitrol almost certainly holds a LOT more water. Can't say absolutely, but I suspect you'll have some severe difficulty establishing sufficient gravity circulation with the Peerless.

The old coal-fired gravity boiler would have had two full-size (same as largest supply pipe branch size) supply tappings coming from the top and likely a single huge (probably 4") return tapping near the bottom. They also held a lot of water.

bernie_3

The mains are not down sized and your guess is correct about the temp sensor. I had corrected my MI-05 mistake in one of my other replies. That should have been a Peerless 61-05. It does have a 3" supply and return and a 2" supply and return. From what I have gathered with my limited research the 61-05 appears to be a pretty good matchup. Any corrections to my rookie viewpoints are greatly appreciated.

bernie_3

Steve, thanks for giving me some hope.

Mike T., Swampeast MO

Looks to me like the 61-05 has single supply and single return tappings--both 2". If you're looking at the drawing that 3" by the return is the distance from the center of the pipe to the edge of the case.

The 62 series has multiple 2" supply tappings but still only a single 2" return tap--output is also WAY above your estimated loss.

Again, I can't be 100% certain, but really doubt you'll be able to get sufficient gravity circulation just piping this boiler into the system.

Constantin

Insulation options...

... our house is currently undergoing a corebond retrofit in the historic part, with Icynene elsewhere (where the walls are thicker).

I stongly suggest that if you want to make your attic floor the edge of your thermal envelope, that you use something more efficient than blow-in fiberglass on its own. That only gives you an R22 at best and with any drafting, you'll see no benefit at all.

Of course, this is of little help considering that you've already insulated and hence aren't in the mood to replace the extant insulation. Thus, perhaps consider installing 2" sleepers and 2" sheets of XPS on the floor with plywood as a protection on top. Seal all the seams and you have a true R30 roof.

Sealing the baloon frame is peanuts if you send someone in to do it with foam. The stuff works great and expands to seal all the cracks. Insulating the perimeter of the foundation is a good idea also, though foam choices are somewhat limited by the environment - water logging and the like. However, once again, XPS can come to the rescue since it doesn't absorb water. See Building Science Corporation for more info - their cold climate builder booklet has become a dense piece of late night reading for our contractor.

As for modern vs. old 3-track storms, I can only say that our old storms were hard to operate, ineffective at preventing infiltration, and hence only good to keep rain off the original windows. The new Harvey's slide beautifully, sit tight, and currently serve as the windows in most of the house, while the old sashes are undergoing remanufacturing/restauration. Such is the life in a historic district.

So talk to your insulation contractors and see what they can do for you. If they use icynene, then they can blow that stuff directly into the walls, with only two holes per stud bay required. As Alex will attest, that's still a lot of holes to patch, but at least you get to preserve 95% of the old plaster walls.

bernie_3

Please forgive a rookie for mis communications. I have looked at a bunch of material and was confused. Take a look at the Peerless 63-04. I believe it will take care of my needs. Thanks again!

Andrew_9

gravity hydronic heat and baseboards

I have a off grid home that uses wood heat.I have a very large coal/wood hot water boiler that I would love to set up with Overhead gravity hydronic heat on this home, gravity as there is no electric power.It is a story and a half so heating on floor would be ample. Could I use a slant fin baseboard system ?could it be done in a loop ?

Mike T., Swampeast MO

No problem

Looks like tappings should be sufficient. Still not sure about the water content as even your current likely holds much more.

A more suitably sized boiler should cut fuel consumption, but I certainly wouldn't expect any radical change as the technology and efficiency are very similar to what you have now.

I do understand why you want to stay with the simple gravity flow, but IMHO I'd wait until the current boiler dies. By then there will likely be more options in the condensing/modulating arena and any with problems will have been weeded out. If your major motivation is to substantially reduce energy consumption and cost, I don't believe you're on the right track.

Bernie Riddle

With your help I think it makes sense to go ahead with all insulation, infiltration issues. Hopefully the boiler will cooperate and not give out this season.

bernie_3

Ken, The more I read this reply the more it makes sense to me. Because the current boiler has a set of 3" and a set of 2" supplies and returns would I need to buy a storage tank with similar fittings to take advantage of the good gravity operation my current piping is giving?

Jeff_39

If they still make powerpile burners I would look for that type of boiler, with gravity hot water you would always have heat even if you lost electricity. I believe all you would have to do is change the thermostat. Would be a good advantage if you lose electric often like we do hear!

bernie_3

We went thru an ice storm here Feb 03. I now am the proud owner of a generator that can run the household in winter.

Constantin

Consider using the waste heat

If the generator is running for a while, consider diverting the coolant loop into the house to help warm it up. We use the coolant on the boat to heat the IDWH, I see no reason that you couldn't do something similar to heat the basement.

For example, Hamilton Marine sells a fancoil + blower combo that is meant to be run off of a engine coolant circuit. You could wire it up so that it automatically starts whenever the generator is running. The more heat the generator dumps inside the house, the less heat you have to supply on your own. These fancoils are on the order of a couple of hundred bucks...

greg_7

I replaced my original gravity boiler, a a very large gas converted coal unit by Gurney--a 406 1/2 C.

I installed a primary loop and pump and installed two smaller Weil Mclain cast iron boilers.

My house has about 4,000 sq feet of heated space with 1,100 sq feet of radiation.

I saved about 1/2 of my gas bill with no insulation.

That's next.

Bernie Riddle

puddle under boiler

Well guys, I have been trying to plan for a replacement for my old beast for this summer but I think it is going to push the issue. Just walked to basement to check something else and found a small puddle under the boiler. It was just finishing a heat cycle and I could see water dripping at the rate of a drop a second from the opposite side of the burner service door. (NG boiler) I have seen on this site in the past the possibilities of using JB Weld for temp patches. Any thoughts pro or con?

greg_7

J-B worked well on a steam radiator I fixed a while back.

bernie_3

j-b

well I tried the j-b last night but did not have any luck. In looking at everything the boiler only leaks during the heating cycle. It takes it about one minute after the burners light to start dripping and drips until about one or two minutes after the burners kick out. I am leaving the water feed line open to make up the loss. Am considering lowering my temp ranges to 160-140 to see if this might help.Anyone with any other thoughts please let me know. I just want to limp in to spring at this point.

Constantin

How cold is the return water temperature?

Perhaps the flue gases in the boiler are condensing due to low boiler temp?

If the drips only happen during/after operation and the water pressure is otherwise constant, I see no reason yet why this should be a leak in the water circuit/boiler... Rather, I suspect it's flue gases condensing on something.

You do have an expansion tank on this system, right?

Dale

pressure

Why not lower pressure? 8 psi will probably work fine.

bernie_3

current set up is 180-160 on temps. We had the covers off last night and fired it up. could not see condensate from top of boiler working it's way down. The temp set up is the same that we have had for the last three years and have had no problems before.

bernie_3

yes on exp tank. it is old style located in the attic. we pulled it two years ago and replumbed to it and also cleaned it out to make sure all was in proper order. as i have said before this is an old gravity system complete with the Honeywell Heat Generator as illustrated in Dan's Q&A paper on gravity heat.

Bernie Riddle

I was mistaken on temps. The current setup is 165-145. While I have never had a condensation issue before I,m sure it is a possibility. It is still only leaking at heatup. It takes about one minute to statr dripping from bottom at the rate of a drip/second. Would increasing to 180-160 possibly remedy or should I let a sleeping dog lie. Thanks for all your input.

greg_7

My old gravity boiler would pressure up when fired and force water out of the automatic feed valve. I eventually ran a 1/2 copper lie to a floor drain to deal with this. The attic expansion tank was removed long before I bought the place.

You also could have a leak between the sections.

bernie_3

It's coming from the wrong place for the feed.As far as between sections that would fit with what I am seeing but I'm puzzled why it leaks only at firing?