TRV's Need Advice

Paul Pollets

A 11/2" pipe nipple will fit into a Fem TRV (38mm.)valve body with special doping requirements...hence "Rorke's Rule". Only Chris can impart the secret handshake.

Danfoss may make an 11/2 valve body, but it would be special order and probably be easier to find in Canada.

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Dale Pickard

Help with Rad Retrofit

Hey folks,

There's a great old historic building in town that now houses a law office that is in serious need of attention to what we think was a gravity hot water system that was converted to forced hot water a few decades ago.
The only things new on the boiler from it's last service are the cold water feed and the vent pipe. There's a rusted coffee can under the relief vailve and a pillow expansion tank shoved up in the joists. The radiators have air vents. The system serves these beautiful radiators. There is one Thermostat in the 3 story building and one B&G circulator. The boiler is a Crane rated at 330,000 btu/hr.

I think that't it's likely is it that the system has been breathing lots of fresh water. The fill valve has been replaced in the last couple of years. It looks like the relief valve has been opening.

We want to replace the boiler with a VitoGas 100 with Divicon or a Vitodens, go to constant circulation and TRV's for the circuits that we can identify that are in parallel. The piping I am showing is 1 1/2" . Are there TRV inserts that fit inside the existing valve?
How is this kind of piping retrofit done.?

We want to leave the radiators where they are. All the dimensions are critical because they are piped at each end on the bottom.

Another question, how efficient is this boiler? The heating system is not very effective. No zoning, no control. A big leaky, but historic and cool building with wooden floors. The bathroom sink hot and cold I note is actually piped in lead. The lawyers all run around in sweaters. : -)

Any feedback would be welcome.

Mike T., Swampeast MO

Good news & bad news when it comes to installing TRVs on those rads.

Good news is that TRV valve bodies are direct replacements for either a hand valve or an angle union. Bad news is that they're only available up to 1¼".

Looks like you might have a problem with those 1½" connections. I don't see any reducing bushing in the radiator tapping. Generally you can just replace the supply riser with 1¼" and you have enough wiggle room. In your situation however, you'll also need a reducing bushing in the radiator to accommodate the new valve tailpiece. Take some very careful measurements and you can probably get things to fit by sizing the supply riser down further--I just wouldn't go smaller than ¾". The modern reducing bushings I get add about ¾" in width--a bit less if you really screw it in hard. The old ones are slimmer (about ½"), but don't know if they're available any more. Don't worry about changing the return side. HIGHLY doubtful that the rads can't be adequately supplied with a ¾" side-mount angle valve. Flow ability is just a bit lower than 1" and 1¼". The straight and angle valve bodies have identical flow ability from ¾" - 1¼". The larger valve sizes are mainly for replacement convenience--not increased flow ability. Check and double-check that you're installing the TRV valve on the supply. Hand valves are frequently but not always on the supply side, so you have to examine the piping. With hidden piping, bang on pipes with a wrench and have someone listen/feel for the pipe you're hitting. If you install a TRV backwards you'll get a "bang-bang-bang" as the valve tries to throttle flow.

If TRV inserts for old valves are available, I'm not aware.

Make CERTAIN that the valve operator is not installed in a draft caused by doors, leaky windows, etc. and that it's not located on an uninsulated exterior wall. Personally, I like the remote sensing versions as you can locate the sensor about 10" up the wall well out of the way of any convective draft across the floor. They do cost more, but not too bad.

If you're going first-class you might want to use remote operation as well as remote sensing. The valve on the floor isn't the most convenient place for adjustment. If you just love nasty jobs, you can alway change the supply location to the top tapping. That puts the operator in a convenient location, but be warned that removing the old plugs is an absolute pain.

Some report that they can remove the old valve/union tailpieces using a spud wrench. I've never been able to do this--the brass lands that engage the grooves in the spud wrench just break off. I just remove the entire tapping bushing and tailpiece then replace the bushing.

With Danfoss TRVs, the operators should only be installed horizontally. The "side mount angle" valve bodies work with that type of piping. Note however that the operators will extend about 4¼" beyond the center of the pipe so watch out for close walls!

As long as the old tank isn't leaking, install a B&G Air-Trol fitting!

Mike T., Swampeast MO

One Other Thing

If clearance against walls is going to be a problem, use the standard angle valve and a remote sensing (or remote operating/sensing) controller. Those can be installed vertically without problem.

Dale Pickard

Thanks Mike

I need to spend some more time investigating this project. I don't believe the tops of the rads are tapped but I think there is a flat ground for it.

1 1/4" is the largest ones we could find as well. Even if the size is right, it's hard to imagine that the fit would be plug compatible.

It's hard to imagine that we could get the piping apart without destroying it. The building occupants have been told not to work the valves.

Extending the piping to the top and drilling and tapping the top of the rad might be an idea. It would give us the room to reduce the piping.

As far as the pillow tank goes, if we touch this project, the whole mechanical room is history. I wonder what peoples experiences are with these systems once they get water logged. How fast do they rot inside. This one has been bringing in fresh water and condensing in the flue. There is all kinds of evidence of condensate on the floor under the burners.....you know, rust.

Dale

Mike T., Swampeast MO

1 1/4" is the largest ones we could find as well. Even if the size is right, it's hard to imagine that the fit would be plug compatible.

Have replaced hand valves and angle unions of at least 3 different manufacturers from ¾" - 1¼" and the TRV body is always a perfect fit. Amazingly, valve geometry hasn't changed.

Every column radiator I've seen is tapped 2" with bushings used for smaller union/valve sizes. Special tapping were available on order so perhaps those are different. Guess there's an off chance that it uses a 1½" x 2" hand valve.

I haven't had any problem drilling and tapping iron rads for air bleeders using just a punch and hand drill, but not sure if I'd try tapping for a ¾" tailpiece without a drill press. At least those rads can be disassembled

Have only done extensive modifications to three gravity systems, but in every case the pipes come apart--repeated dousing over a few hours with cheap silicon spray (the type that lists petroleum distillate as the major ingredient) works on even the most stubborn joints. I always try to use two wrenches, but sometimes you just don't have access. Spray, wait, spray, wait, spray wait then disassemble. On rare occasion you collapse the pipe, but you're replacing it anyway... The valves and unions (being brass) have always been easy to remove without any damage. The tapping bushings are a bit¢h, but with a 36" or 48" wrench and a long cheater bar, they eventually come loose and I've never broken a rad that way. They've likely been told not to operate the hand valves because the packing needs to be replaced and "if you move it, it leaks".

Sorry, no experience with "pillow" tanks. All I've encountered/worked on are cylinders. They seem to last forever and the B&G Air-Trol stops the waterlogging problem at its source (gravity circulation into the tank).

Mike T., Swampeast MO

Another Thing (again)

If you decide to move the valve to the top and you have to tap, you might be able to get by with ½" valves. A ½" Danfoss TRV will give about 2 gpm flow with pressure drop of 2 psi. Such is still well within the "safe" range for quiet, long-lived service. Since you can consider head loss in the piping itself to be zero (head loss in gravity systems is measured in milinches), you're still not talking about a significant delta-p. BTW, with three stories you get about 3,660 milinches (or .132 PSI) of gravity motive force so your head loss has to be less than that--about 1/3 less as you go down each floor. That's why you can essentially forget head loss in the gravity mains and branches.

The largest valves are most likely on the ground floor and closest to the boiler. Those farther from the boiler are probably a size smaller and those on upper floors at least 2 sizes smaller. ¾" is the smallest gravity branch I've ever seen.

When it comes time to size the circulator for the radiation (presuming TRVs and constant circuulation) don't forget that your flow requirement plummets. Instead of the 30 gpm or so that a B&G 100 can deliver into a system with almost no head loss, the little circulator built into a Vitodens 6-24 proved perfectly adequate for my system with a touch over 1,000 sq.ft. EDR of radiation.

Mike T., Swampeast MO

Regarding Supply Temperature

Dale:

Know you like to design radiant systems with high heat transfer ability, very low supply temps and return temps at/near ambient.

Standing iron has extreme heat transfer ability, so that's no problem. A gravity system with TRVs is also fully capable of return temps at/near ambient. Empowered by a Vitodens, you can also keep very low supply temps. (How low everything goes depends on the degree of oversizing of the radiation and the balance of the radiation among the spaces.)

BUT, my experience this past heating season is that you can't let the supply temp go too low. You may well maintain the TRV settings with a very low supply temp, but comfort suffers if you're also trying to maintain the lowest comfortable air temperature.

After all, standing iron radiators aren't floors

With no changes in the envelope, my radiators (always under full reset and constant circulation) ran cooler with the Vitodens compared to the old plain cast iron boiler. Delta-t across individual radiators decreased. (ERROR--first wrote that it increased--NOT CORRECT!) Problem is that it depends on where you measure the supply temp At the boiler it increased, at the radiator it decreased...

If I reduced supply temp to slightly decrease delta-t across individual rads, comfort suffered. For comfort, the rads seem to need a small amount of warmer iron--even if the average temperature is unchanged.

One way you loose some efficiency by increasing supply temp--the other way you loose some efficiency by increasing ambient temp.

The "sun" and "moon" dials are the key and NOT operated in the way you'd expect... There's still a place for an external outdoor temp sensor with a Vitodens...

Robert O'Connor_3

trv

look at our website. www.maconcontrols.com we can make inserts and retrofits for any size rad valve. tp

c.t.kay

call tunstall / macon look on the virtual trade show for info

John Reynolds

tp is right on they helprd me out with some custom made heads for stem they were 1 1/2 and 2" very easy to install

Goodluck

Mike T., Swampeast MO

Will definitely slash installation labor in larger valves. Must say that I'd question if they can approach the indefinite lifespan and simple service of TRV bodies.

Dale Pickard

Thanks Mike

For all the attention that you put to this question. I pretty much soaked it up. I'll have a conversation with my guys putting this estimate together and we'll certainly consider your comments.

I could see drilling the upper flats. The rotabroach cutters that I use to bore big holes with my milling machine were originally developed for use with magnetic base drill presses, (I think). To put holes in I beams for rivets. Possibly that hole could be drilled square using one of those. The rotabroaches cut a clean hole with very little power. I'm sure the iron is pretty soft stuff.

Rather than tap the hole, I'd be tempted to silver braze a male nipple into the radiator.?? I don't know the wall thickness and how many threads might be cut.

The Vitodens is limited to about 220 btu/hr and 167°. I think the VitoGas 100 with the divicon could be more generously sized and reach elevated temps without difficulty. These rads and this building might want to see 190° water when it's 40° below. Even the Vitogas 85% efficiency will generate significant efficiency gains over what they have. We will have to line the flue with some stainless whether we use the VD or the VG.

The TRV's would give them some control for the first time. The control would mostly increase effectiveness but should result in some energy savings as well.

The horizontal cylinder tank is what I'm referring to as the "pillow" tank. Meaning...not a diaphragm expansion tank. I am aware of the B&G stuff like the airtrol.

This is the kind of project that we wouldn't touch except to completely re habilitate it into something that we are willing to service.

Thanks for your help. I'll keep you posted if we go anywhere with this.

Dale

Dale Pickard

Thanks

I'll be giving you a call Monday. I don't suppose that you recognize that valve?

Dale Pickard
President
pick@radiantengineering.com
Radiant Engineering Inc.
501 E. Peach
Bozeman MT 59715
406.587.6036
406.587.1617 fax

Mike T., Swampeast MO

Rather than tap the hole, I'd be tempted to silver braze a male nipple into the radiator.?? I don't know the wall thickness and how many threads might be cut.

Sorry, zero experience with that. Did though watch someone try to braze a cracked radiator--completely unsuccessful. Personally, I'd start with one in an out-of-the-way place

These rads and this building might want to see 190° water when it's 40° below.

Presume it's an old solid masonary building with the envelope pretty well original. Getting the original windows in top-notch shape is always a good step with historic buildings.

Have never felt constantly circulated, TRVd rads in cold climates like yours, but in this area they run amazingly cool even in the coldest weather around zero. Would imagine that the building has quite an abundance of standing iron... Unless they want to use deep, daily setbacks in bitter cold weather, you'd probably be surprised just how far 170° or so supply can go.

Paul Pollets

TRV's for 11/2\"

Dale I renovated the Meeker Mansion in Puyallup, WA. and replaced the 11/2" TRV's with Oventrop valve bodies. I got them from Chris Rorke at Blueline Supply in Jackson Hole, WY. He's a fabulaous resource and also an ME. He taught me how to thread up from metric to English threads without a leak (Rorke's Rule) I was skeptical, but can fully testify that Rorke Rules. I've sandblasted the nickel plating off the valves to "age" them, when required. The Meeker Mansion renovation is featured on the ART website, icluding dual Vitogas 100's and a 4 way mix. with lead lag controller.

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Dale Pickard

Brazing clean iron isn't too difficult

An exhaust manifold is too dirty. I watched my welding prof gas weld a crack in an exhaust manifold once. He put it in an over first and brought it up to temp and welded the crack with iron rod about as big around as your pinkie. Did a perfect job.

Dale

Dale Pickard

By "thread up from metric to english" what do you mean? What is the process. What is the metric equivalent of 1 1/2", (38.1 mm). What's the nearest smaller size, 35 mm?

I've thought that it sholdn't be too difficult to design have new brass tailpieces and have them turned to fit a existing valve. If oventrop has a valve that is close in dimension, I'd go this route I think, so that things really fit correctly.

Paul, thanks for your reply. I'll check out the Meeker mansion.

Dale

Dale Pickard

We've done similar things

Mating english straight threads to english tapered and metric to english. We've used Loctite 277 and 638 in those situations. It works well and fittings can only be removed with heat, (several hundred degrees) which softens it. Woe be to the one that puts a pipe wrench on a loctite nipple without knowing it's loctite and heating it up first. ; -)
I'd rather have my threads match.

Dale