Gravity Hot Water Upgrade

mfader

As a historical architect I work to understand and maintain existing gravity hot water systems with their 19th century radiators. But I am not a plumber or mechanical engineer! With all that I read on your website I have learned a lot of respect for the original heating systems which makes me uncertain when it comes to upgrading the system. I do not know how to choose the best contractor. By upgrading I am referring to introducing zones, installing Pex by removing some or all existing pipes, how to properly size circulators, and converting oil to propane. How can I choose the appropriate contractor and know that the proposed improvements are correct?

icesailor

If you are who I think you are, where you live, it won't be easy. Most anyone will want to rip out all your radiators and convert the whole antique house to scorched air.

With duct board and flex duct run everywhere.

Paul48

That's rather confusing, because in one sentence you talk about preserving. In the next, you talk about completely changing. The required skill set for a contractor would be very different, depending on the job.

mfader

Maintaining the existing system is considered a level of preservation tho I understand there is a combination of old and new. Nothing is being completely changed.

I'll try my question in another way: is there an upgrade to such a system that could be a major mistake?

Paul48

Yes...without a complete understanding of how the system works, any changes to pipe diameter, pitch, or placement, can make the system stop functioning if attempting to maintain gravity circulation. If you're attempting to convert to a circulated system, it's important to not over-circulate.Here's a link to an article by Frank "Steamhead" Wilsey, about selecting circs for a gravity conversion.
https://heatinghelp.com/systems-help-center/sizing-circulators-for-old-gravity-hot-water-systems?stage=Stage

Jamie Hall

Do read the article by Frank -- he's the real guru. But I will plunge ahead anyway with a couple of comments. The most important of which is that it may be possible, depending on exactly how you want to do the zoning, to do all the necessary repiping in the basement. This has the major advantage of not requiring work in the main part of the structure, which has the potential to damage historic characteristics or be frighteningly expensive (trust me: been there, done that) to replace the historic materials correctly, in kind.

Paul Pollets

I've restored or replaced the hydronic systems in several historic buildings, Including the Meeker Mansion in Puyallup, WA, where Ezra Meeker lived (pioneer and founder of the Oregon Trail) The project added several rooms that weren't heated, replaced the boiler with (2) Viessmann gas boilers that were staged by computer control; adding TRV's to all the radiators, and sandblasting and powder coating most of the existing cast iron rads. The new system is very efficient and dropped fuel costs 40%. The most important thing was to leave the system on 1 "zone" rather than provide numerous sub-zones. The TRV's allow each radiator to be adjusted while the "constant circulation" keeps up with any temperature change outside. If using propane, I'd use a condensing wall-hung appliance sized accordingly.
I'd call RST reps in and ask Richard Trethewey for a local expert. http://rstthermal.com/

icesailor

@Paul48:

Please don't think I am following you around to be contrary with you. Whether I know who this person is or not is inconsequential. For the sake of discussion, I don't. But I dealt with this scenario many, many times over, working on Antiques.

Say you get a call to look at an old house that is almost 200 years old. But about 100 years ago, someone did what we would call today, a gut re-hab with a top to bottom renovation. In the process, maybe they had two boilers installed. One oil the other Coal, all gravity. The whole house is still museum quality with original radiators that you only find in salvage yards, The Smithsonian or Steamhead's customer base. Its already been converted to forced hot water.

So, you're asked to look at it. The system is in excellent shape and well maintained. Not a leaking radiator or pipe in the whole place. The 30+YO oil boiler has earned a rest. Connected now to an indirect. The system on two floors and a large square floor plan is all on one zone and one thermostat does the entire house. What to do. A closer inspection reveals that the old dead wet heads piped the entire house with 4 circuits. N, S, E, & West, 1st and 2nd floor. And because you know that those old dead wet heads knew how to balance big gut re-hab'ed houses. So, split the system into 4 zones with zone valves and add a Taco "I" Series valve to control it with ODR and boiler protection.

Someone else looks at the same situation as "Rip out all this steel pipe, and fish 1/2" PEX into the wall, Manifolds and home runs in the cellar, and TRV's on every radiator." There's about 30 radiators. How much is it going to cost? Just for the TRV's that don't work on the floor.

Cost is an issue. And no 200 year old pine floor will be wrecked accidently while trying t get 100 year old radiator fittings out.

The issue of how the gravity system is pumped isn't at issue. Its how to take an antique system that has been going fine for years, and make it better without making it look like Greenwich, CT threw up on it. I've worked in antique houses that were gut re-hab'ed and put radiant in the ceilings so that you didn't have to see radiators. Not everyone has a wallet like that.

Sell what you can at a price people can afford.

Or someone else will,

Paul Pollets

I'm not sure what the point is, but historical restoration usually means make minimal invasion into the structure and make the new system as efficient as possible. The project I referenced (Meeker Mansion) had 4 quadrants of piping. We left them be and simply added new radiation to several of the piping quadrants where pipe sizing allowed. We used Pex-al-Pex in the basement and within walls, but transitioned to black sch 40 piping where visible.
As to cost, all systems have a cost and restoring or replacing systems in old historic buildings typically have a higher cost. The owners have to deal with a realistic budget and hopefully, the contractor has a very high skillset. I've seen where TRV's are not used because the contractor or the Mechanical Engineer wasn't aware of them or perceived them as " not cost effective". I've seen boiler controls (ODR) left out of a project simply to save some money. I always look at the system with regards to how to bring it into the 21st century and present the proper specs and budget to the right person. There are very few who can write a proper spec for restoring old systems that have historic implications. That often puts it in the hands of someone who may not know what to do. We've all been witness to that if you've long trade experience.

Jamie Hall

Paul is absolutely right on this one (I'd love to see the job on the Meeker mansion!). The main thing to understand is the distinction between historic restoration and renovation. In the former, one is trying to restore -- quite literally -- the building to some previous time period (in the museum I take care of, it's variously 1893 or 1880, depending on where in the building, for instance) using, to the extent possible, original materials, finishes, and so on -- and tolerating "modern" additions, such as a heating system or electricity or plumbing -- by restoring them to the original condition to the extent possible. This may mean, in some cases, new materials (e.g. lead pipe has got to go) or new arrangements (1930 wiring is just not usable...) -- but one does the minimum.

Keeping the original radiators and piping, but equipping them with TRVs, is very much in line with accepted restoration techniques.

In renovation, however, pretty much anything goes -- it's a very different game.

Most competent contractors can handle renovation work. There are very few who can be trusted with restoration, and one needs references and interviews and, preferably site visits.

Ironman

I could not agree more with what Paul and Jamie have said.
I would also recommend that you avoid zoning - particularly if mod/con boilers are used - and go with TRVs at each rad.
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I would also recommend that you leave the large piping intact, unless it has issues, if mod/cons are used. Mod/cons are low mass and can short cycle if there's not enough mass in the system for a buffer. The old piping, with its high mass, is an excellent buffer.

In regard to finding a contractor: check the contractor locator on this site or post your locality and others on here can recommend one.

mfader

Thanks for all of your great suggestions! I've been following up on your suggestions by reading Frank Wilsey's article and learning what Mod/cons and TRVs are, etc. It's a lot of homework for a non-plumber/engineer but I do need to be able to understand the language, assess systems and know how to evaluate proposals. What I have been receiving from contractors consists of lists of parts which I cannot translate into the articulated descriptions of systems that you are all so good at.

One of several projects is exactly the system that ice sailor described: an excellent 19th-century system already converted to forced hot water with a potential for zoning through the existing lines. This project is focused on improving the efficiency of the system only - no other work at the house. I think all of the large piping can remain intact in the basement, first and second floors. With a Weil-McLain boiler installed in 1995 this 200-yr old, uninsulated house of two floors (plus unheated basement + attic) totals 3080 sq. ft. and costs $4500/year to heat with an assortment of (18) cast-iron radiators in great condition. Definitely looking for greater efficiency and less cost.

What I am understanding from your comments is a difference of opinion on 'zones or no zones'' and 'TRVs or no TRVs' . I will call RST thermal and ask for their recommendation. Thanks again!

Paul48

Start at Taco's FloPro University. It's free, and there is an incredible amount of information. You'll find yourself staying up late, and you'll have a much better understanding of what is needed to heat a home,as efficiently as possible.

icesailor

I started this this AM. My wife had her other knee replaced. My bionic wife. 2 knees and a hip. I've been doing my nursely duties. Doctor this AM

There you go. You just made my most important points. COST!!!!

The one thing we have all agreed to not discuss here, So, its like the Elephant in the room.

An old late Yankee friend used to tell me, "If they call you on the phone, they want to spend money". What he didn't discuss was the fact is that being in business, you had to have the ability to figure out how much someone was willing to spend and what they were willing to spend it on.

None here envision the imaginary home I imagine that needs updating. No one knows how much someone is willing to spend or the extent that they might over extend themselves for. It wouldn't matter to me what or how it was, I see it the same. People will always spend the least amount of money they can if they can. If you or your wife wants a BMW, you all want a 7 Series ($110,000+) but end up settling for a 3 Series ($40,000). Reality sets in. In the case of the old house, all the parameters have been set forth. Old radiators in good condition, large pipes in the cellar that don't leak and are in good condition. piping set up in ways that can change the fact that one thermostat runs the whole house. Have any of you all been to a job where someone installed a lot of equipment and the cost and comfort level haven't really changed? Meet one, ME. So, when I tell someone and put it in writing that savings depend on insulating the uninsulated pipes in the cellar. Which was once covered with asbestos and was remediated. The old dead Wetheads always did that. Then, the old dead Wetheads conveniently started all the circuits with piping that was 2". So, if you break back to a fitting, there's no BS about threading with a geared threader, You can split the whole house into circuits. You never have to leave the cellar. Replace the boiler. Remember, a complaint was the ungodly amount of oil burned. There is no possibility EVER of Nat Gas being piped in Propane and Oil are comparably priced. Or so they say. So, that basic package gives the homeowner a place to start. Because if you convince them to go with all the Mod-Cons, PEX and TRV's after demolishing everything in the cellar. (I want to see that), the price for all that will be way considerably higher. And no matter what the efficiency of the new system, the fuel bill might go down slightly. No where near expectations for the ROI.

I figured out that you need three things. Least common denominator, one in the middle and the full Monte. Most picked something in the middle, a few picked the first, and no one ever picked the Full Monte. Unless there was an architect involved who wanted the commission sales on what went into the job. There was usually a fight over something.

Some people just can't think down, but only up. Up meaning more costly. It gets back to the new BMW. They all want the 7 Series, and if you give then all the options priced out, they might buy the 3 Series with more options. The might even buy a stripped down Series 5. They'll take the 7 Series if you'll give it to them at the same price as the 5 Series. They already know of a used (almost new) 7 Series on CarFax.