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Mark Mentovai

Mark Mentovai

Joined on February 14, 2006

Last Post on December 14, 2006

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Supply house

@ December 14, 2006 5:19 PM in how comes Honeywell

Does your supply house know about these? They're all SPDT (series 20/power-open-power-closed-compatible) thermostats in Honeywell's current pro line. Mark

You want SPST break on rise

@ December 13, 2006 4:38 PM in Correct vaporstat replacement for Pressuretrol

The -J1009 and -J1017 have an SPDT switch that switches R to B or R, the same as the L608 mercury vaporstat. Ignore the W terminal. Just pretend it's not there. Treat it as though it were an SPST switch, R to B only, break on rise, make on fall. The -J1025 and -J1033 are direct replacements for the L408B, none of which have any place in your application. I'm a little surprised that the PA404 has 24V listed. I can't think of a reason that the L408J wouldn't work at 24V, but I wouldn't do it since it's not a listed application. I think that these controls are better placed on the line voltage side, anyway, in series with the low water cut-out. That's a better way to go than adding an extra relay. Mark

Piece of cake

@ December 13, 2006 3:42 PM in T-stat for 1-pipe steam sysyem

Your description sounded just like an original Chronotherm, so I moseyed on over to Honeywell's site and searched their literature for "chronotherm." An ammeter's really the best way to do this, and they're pretty inexpensive. But if you know exactly what the thermostat is connected to, then you can check that device's nameplate to figure out how much current will be pulled through the thermostat. This depends on your system. The thermostat might be directly connected to an oil primary, or a gas valve, or a relay, or a zone valve. (Well, it probably wouldn't be a zone valve on a steamer.) In a simple heating-only steam system, you'd usually be looking at the oil primary or the gas valve. Mark


@ December 13, 2006 2:50 PM in T-stat for 1-pipe steam sysyem

Sounds like an old mechanical Chronotherm. It's similar internally to a mechanical T87, except for the timer. Both use mercury switches mounted on a bimetallic coil. They've also got anticipators, and you should probably check the setting before condemning it unless you've already made up your mind about a new thermostat. Is this what you've got? The anticipator is shown on page 22. The recalibration that Bill describes is shown on page 25, but it doesn't sound to me like you need to do this.


@ December 13, 2006 12:06 PM in Correct vaporstat replacement for Pressuretrol

Mel, according to that PDF, you want L408J1009 or L408J1017, and you want to use terminals R and B. The difference between the two is that one has a 1psi main scale and the other has a 4psi main scale. If you don't need more than 1psi for cut-out, you might want the lower-range model to give you more precision and to prevent a future knucklehead from turning the pressure up too high. A Honeywell distributor, whom you need to order one of these through anyway, will be able to help you figure out which is which.

Gorton 54

@ December 11, 2006 3:08 PM in Gorton 54 disc type vent valve

As far as I'm aware, this isn't something you should find on a steam system, it's meant to separate air from water and vent it in hot water systems. You should bush the 1/4" down to 1/8" and use an air vent intended for steam.


@ December 11, 2006 3:01 PM in Reading a pressuretrol--dumb question?

On the PA404, the number that's facing the front of the control on the differential wheel is the differential setting. You turn the wheel all the way to one side for a differential of 1psi.

Let's go back to basics

@ December 10, 2006 12:24 PM in What happens when a pressuretrol breaks?

The pressuretrol and pressure gauge are two independent devices. One doesn't belong to the other. But if they're both mounted on the same pipe, and that pipe is clogged, neither of them are going to see very much pressure. (Of course, the same could happen if they're mounted on different loops.) When a gauge doesn't see pressure, it won't move. When a pressuretrol doesn't see pressure, it won't shut the burner off. Now, the pressuretrol is being used as a safety control here, but even if it's not registering any pressure at all, you've got a 15psi relief valve piped into the top of the boiler. Or, at least, you should. That's another safety. If pressure builds to that point, the relief valve, and not your boiler, will be the first thing to give. It'll shoot steam all over the place, and you don't want to be in its way when that happens, but at least your boiler won't explode. But don't worry. If your boiler is able to heat your home, chances are that you'd overheat before anything to to that point. The fact that your burner is cycling on and off makes it less likely that you're building that kind of pressure. (You can give your boiler a high-limit-only manual-reset pressuretrol, preferrably on its own pigtail, as a safety control to shut things down if your operating pressuretrol is out to lunch, before popping the relief valve. But it's an added expense, and most homes don't get treated to these.) In a typical steam system - and I don't know if yours is typical or not - there are a few things that can shut the burner down: - Thermostat. When the thermostat is satisfied, it will end a call for heat, and the burner will stop. - Pressuretrol or vaporstat. While the thermostat is calling for heat, this will turn the burner off when the pressure rises to a setpoint, and start it back up again when the pressure drops. - Low water cut-off. If the water level in the boiler is too low, this will interrupt the burner to protect it from firing a dry boiler. Dry boilers can crack when heated, and if you add water to them, they can explode. - Burner primary control. If the flame goes out when it's not supposed to, this will stop the burner to avoid spraying fuel into the combustion chamber without burning it. The last thing you want is a puddle of oil in there, waiting to go BOOM when you finally manage to establish a flame. Any one of these things can cause your burner to cycle, although it's not normal for the low water cut-off or primary control to be cycling the burner - and if they are, you need to have someone look at your system. Older primaries would lock out immediately if you lost flame while the burner was running. Some of the newer electronic ones will shut the burner down for a minute and then try to relight - although there are safeties built in here, too, it's still possible for it to mask marginal-combustion problems, making them appear to cycle your burner. Based on what you've written - specifically, that you see an arc in the thermostat's mercury tube when the burner cycles - I'd suspect a thermostat problem. But nobody's going to rule out other possibilities from this distance. I'd suggest that the anticipator may be set incorrectly. If you've got an ammeter, you can easily measure a baseline for the proper setting. If not, look for the current (amperage) rating on the primary control, although this can really depend on how the system is wired. If the anticipator is set improperly, you can damage the thermostat and wind up with no heat. And, for peace of mind, you should really have the guys who installed the new burner take a closer look at the whole system, not just parts. Safety's important, as it seems you agree. Mark

Temperature-sensitive element

@ December 9, 2006 7:57 AM in vent question

An air vent has a temperature-sensitive element. It's either a bimetallic strip or a sealed vessel containing a mixture set to boil at a specific temperature slightly less than the temperature of steam. Lost Art describes the operation of the latter in detail. In both cases, the temperature of the steam causes the valve to close. A float is also provided to close the valve in the presence of water. In the case of pressure-vessel vents, the vessel itself doubles as the float. Mark

Gortons don't? That's news to me!

@ December 8, 2006 11:17 PM in vent question

As far as I know, Gortons close against water. They've got floats inside - you can hear 'em - and mine have never spit. To be sure, stop by and e-mail them or give them a call.

Pressure relief valve

@ December 3, 2006 7:29 PM in No heat!

I labelled the pressure REDUCING valve, which is the fill valve. That's the one that you use to let water into the boiler. I didn't label the pressure RELIEF valve, which automatically opens if the pressure gets too high. You can also use it to manually reduce the pressure a little bit. The two valves look similar but are very different, don't confuse them! The pressure relief valve on your boiler is coming out of the top. You can see it in the far corner on your picture. It's the one with the pipe coming out, and heading down toward the ground at an elbow - that pipe ends, open, before reaching the ground. If you lift the handle on the relief valve, it'll let some water out through that pipe, reducing the system pressure. You might have slow drip for a couple of days, but it'll eventually stop. Your boiler pressure is related to the maximum height of the system above the gauge. Unless you've got really high ceilings or three floors, 20psi is high. You can drop it down to the 12-15 range. Mark

SPDT Honeywell Thermostats

@ December 2, 2006 7:14 PM in SPDT Thermostats

The old mercury T87s are no longer being made, but I thought that new mercury-free thermistor-based T87s were available now. It's a classic, how could they kill it? The catalog shows T87K as the new mercury-free T87F. It looks and acts like a mercury T87 on the outside, and it wires up just the same, but inside, it's an electronic power-stealer. You'll find cycle rate switches instead of a heat anticipator. The magic phrase when dealing with Honeywell is "Series 20," which is what they called their 3-wire power-open/power-closed control system. Their literature may not say SPDT, but if it says Series 20, that's what it is. Here are some SPDT options: T87K: Electronic mercury-free non-programmable round T822G: Mechanical (bi-metal) non-programmable TH5000 series: FocusPRO digital non-programmable TH6000 series: FocusPRO digital programmable TH8000 series: VisionPRO touch-screen programmable For the T87K and T822G, you get SPDT switching either R-W or R-Y right out of the box, just like the SPDT mercury T87. For the digital ones, you need to configure the thermostat for 3-wire heat-only operation, otherwise, the Y terminal will be used for cooling. Mark

Glad to help

@ December 2, 2006 5:13 PM in No heat!

Glad to help, guys. It might not be such a bad idea to provide customers with similar diagrams after installations.


@ November 29, 2006 10:50 PM in No heat!

I've labeled the valves in this picture for you. Try to purge from the blue guys on top - use the one that goes to the second floor, if you can figure out which. One of the blue valves up top is hiding behind another pipe in your picture, but I found him. If you want to use the one I've labeled "alternate purge," leave the red one on top that I've labeled "close me" open. When you're done, put all the valves back the way you found them.


@ November 28, 2006 1:05 PM in Old Radiator EDR to BTU

Best of luck with your project, Tim!

You're on the right track

@ November 28, 2006 9:46 AM in Old Radiator EDR to BTU

Square feet EDR is a measure of the surface area of radiating metal. Heat output might vary between radiators of the same dimensions when they're different types. The idea is to consider the surface area - the interface between the hot steam or water inside the radiator and the cooler air in the room - to level the playing field. Here's an online guide that describes cast iron radiator sizing, with charts for standard radiator types: Dan's Lost Art book has even more charts for standard radiators, and the EDR book has sizing information for more esoteric radiation. Mark

RA2000 1PS

@ November 25, 2006 12:46 PM in Danfoss Valves on Single Pipe Steam Systems

Because you've got a one-pipe steam system, your only option is a thermostatic valve on the radiator's vent hole, like the RA2000 1PS. If you fit an RA2000 1PS, you should use a straight-shank air vent, to guarantee that condensate drains from the vent. You can't use a thermostatic valve in place of the supply valve, like the RA2000 non-1PS. Those won't work on a one-pipe steam radiator. They throttle the steam supply, but because the same pipe is used to drain condensate, you'll wind up with water hammer as steam blasts away the water that's in its way. If you've got the thermostat in an unheated space, the worst case scenario is that all of the Danfoss valves close, and the thermostat keeps calling from heat. The burner will run short cycles to maintain pressure, but nothing's going to get any warmer. I like the thermostat in a heated but lightly-used space, with a smallish radiator, smallish vent, and no TRV. You want the thermostat in a heated space so it knows when to turn the system on and off, but you don't want a TRV on its radiator because if the TRV is set to maintain a lower temperature than the thermostat, the thermostat will never stop calling for heat. A heat-timer is an alternative to a thermostat that's especially attractive when you can't find a good spot for the thermostat - like when you don't want to put the 'stat for the whole building in any one tenant's apartment - but they're expensive and I've never played with one. I really like these little valves, and so do the formerly-broiling tenants. When you use 'em properly, they work well and you will save fuel. Mark Another apartment building guy

What if I have condensation and not a leak???

@ October 11, 2006 5:48 AM in New Boiler

Can you tell from the previous pic which was taken 2 weeks ago just after cleaning and this one taken today if this is condensation or a leak? Both pics are of the return side with the drain valve on the right and the return line coming in on the left. I do have pics of the supply side which has minute "leaks" compared to the return side. Remember no bypass and large volume system with old CI radiators and the temp gauge on the boiler has only been running 120-140F recently which should be causing condensation. Also, I always close the cold water fill shutoff valves and never need to add water unless I drain the sealed expansion tank. If it's just condensation and not just small leakes would it pay to just add a bypass, outdoor reset and vent damper and hope it will last another 10 years or should I go for the new install?