What happens when a pressuretrol breaks?

Unknown

Any #`s on this pressuretrol you can give us? Your losing me with the "clock" statement.

Angela_2

Please help! Is my pressuretrol broken?

Hi,

My newly installed burner keeps shutting off, but the pressuretrol (mercury tube) doesn't tip when it does this. The clock doesn't move, ever as far as I can tell. Is this device broken? Can a pressuretrol still operate without it's clock? Is there a way to be sure?

If it isn't the pressuretrol shutting off my burner before I get to temp, does that mean it's the thermostat?

I could really use some advice on this. I have been studying and studying THE BOOK, but I guess it assumes a lot of rudimentary heating knowledge that I don't have, nor have I been able to find a heating guy who has it (here in Rhode Island).

Jim Pompetti

How

does it restart ,do you just wait or do you have to push the red button on the burner?

Angela_2

Yeah! A hit.

Hi Jim,

Thanks for responding. It restarts minutes later. The house has heated up to 65-68 but won't go any further (stays about 8 degrees below the thermostat call). The thing is keeping the steam going, but it is my understanding that this stopping and restarting is a bad thing.

I have actually described it all in a post yesterday-- I think it mentions the Burner short cycling -- is pressuretrol even working -- but I didn't get any responses so I tried again.

I am beginning to suspect the thermostat. I asked two heating guys to look at it, but they didn't conclude anything.

Angela_2

Clock

Sorry, I got that 'clock' term from the fellow that installed the burner. I think it would more correctly be termed a gauge, the dial that gives the reading of actual pressure in the system. It reads zero pressure and never moves. I had the guy adjust the settings, he didn't turn it down exactly as I wanted, but did lower the settings to cut-in at about 1.75 with a differential of 1. It had been set quite a bit higher (I think it was cutting in at around 3 with a differential setting of 2-2 1/2. I was afraid to make him take it down further without seeing to other things in the system, such as installing the main vents.

Unknown

Thanks for clarifiying that,,

So, it seems your burner is not operating long enough, what kind of thermostat do you have? Can you describe it?

Angela_2

The thermostat

This is a very simple round thing by Honeywell, looks exactly what every novice picture when they think 'thermostat.' There's a dial that you turn to the temp you want (this registers on top) and the actual temperature at the thermostat on the bottom. When you take off the cover, there's a mercury tube, a coil, and a strip with numbers on it. This is what the burner man adjusted. He said it was an anticipator, and it was set to 9, he changed it to 4. I changed it to 2.

I told the first heating guy who was here that I thought the thermostat might be a problem, because I could swear that it used to 'click' whenever I turned it up even a couple of degrees, then I'd here the boiler fire downstairs. I wasn't hearing that clicking when I dialed it up-- but I couldn't be sure what was what because I'd been on vacation for 2 weeks and it's hard to remember if something like that is your imagination or not. And since the burner was dead, maybe that was why I didn't hear it click. But anyway, I told the fellow about it and he sniffed around it a little, but he focused mostly on the burner (which he gave up on a little later-- suggesting that his company would put in a brand new one for $2000!).

The fellow that actually replaced the burner looked at it to. He changed the anticipator setting, but now that I'm thinking about it, I am sure that I never saw these big gaps between what I'd set the thermostat at and the temperature it achieved. When I looked at my thermostat set at 72 degrees, it registered 72 degrees or the burner was firing. If I turned it up even a little, I'm sure that the thermostat clicked and the burner reacted.

It is not reacting like this now. I have to turn it up nearly 10 degrees to get a reaction, and it isn't an instant reaction either. Where is the clicking?

I think that unfortunately I'd dissuaded these guys from checking it out as thoroughly as I would have liked, because I told them that I'd already checked the power to it and it was there. They saw the old burner and focused on that.

Unknown

That type of stat,,,,

will not "click", you must be thinking of another. The anticipator should be set to the rated amp draw of the burner relay, I`m guessing about 4, but a meter should really be used. If it`s too low it will stop the burner prematurely.
Also, since it`s "mercury-type", it must be absolutely level on the wall.

Angela_2

Thermostat and Pressuretrol

Hi Dave,

Since the cover has been off, I've seen it flash (like a spark) and click then, but I haven't been able to recreate it. I saw it do it last night from about 6 feet away.

I don't think I was imagining the click, but it's possible that I've confused when the clicking happens. It was one of those things that happens just outside of your awareness, because everything was working fine and I wasn't trying to solve any problems.

How do you check that a round thermostat is level? Of course it's been here forever and hasn't moved, so I assume that it is.

Crap, I don't have a meter. I have half a mind to just replace it (the thermostat) myself today. I live in fear that the burner guy won't come back promptly, I get the impression that though there is a lot of agreement about the need for main vents, no one really wants to drill and install them. But I may just be paranoid. He did say he would come back, check out the pressuretrol, do a cleanout, drill the vents. But I could end up at the back of the line as no-heat situations take priority. Meanwhile I fear I am wasting loads of fuel.

Any thoughts on my pressuretrol question? What does a boiler do if these things aren't working?

I'm afraid that all these books have done is open up can after can of questions in my head. I could start about 10 threads right now. Especially since I have 2 boilers (one ancient; one modern), 2 systems (piped completely differently). Besides my own problems, I just discovered that my tenant's boiler is undersized-- no pickup factor was used at all.

Angela_2

Meter be damned

I just took a wack at it and moved the anticipator on the thermostat back to the left (no science). The burner kicked on and ran until the thermostat setting matched the temperature of the room, then turned off.

Yeah! It has been short cycling since the install on Thursday.

But what about this pressuretrol problem? If a pressuretrol doesn't work, what stops the boiler from blowing?

[Deleted User]

Let's go back to basics

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

Angela_2

Thanks

Hi Mark,

Thanks so much for your explanations. I feel a lot better about my pressuretrol malfunctioning (pretty sure that it is). There is a little gold thingy on top of the boiler, I think this must be the additional safety you were speaking of.

It WAS the thermostat making the burner shut off. I don't have an ammeter, and can barely see the little numbers. I took a chance and moved the thing a little to the left. Not scientific, not accurate and I hope it doesn't break it.

But it did work, the burner ran continuously until the thermostat temp was met, then shut-off. Time will tell how long before it kicks on again, and how long it runs for. The short-cycling has stopped though, so I can't help feeling relieved. The heating guy wouldn't give me a commitment on his return date next week, so I don't know how long I'd have to live with it before we can address the other improvements I want to make to this system (esp. main vents).

Thanks so much for your instruction. I have to admit that this is all stuff I never wanted to know, but necessity is the mother of learning. There are too many hacks in this world, and it makes it worse that they are often really nice, well meaning people who do have loads of skills that I clearly don't have myself, but with lots of gaps in understanding why they do the things they do or why they should be doing it differently. And I can't screen contractors unless I know what to look for. Many really don't like it when a woman is questioning their knowledge (or perhaps when anybody does).

At least the fellow who installed this burner knew about Dan's books, about main vents, about low pressure systems, etc. He was able to answer a lot of the questions I had about my system (I couldn't understand where my return was, because the main runs around the basement and comes back into the boiler-- I couldn't find the end of the main or a wet or dry return!) I hope he comes back next week. I'll be so happy to have main vents, a working pressuretrol and gauge, and a burner firing to the correct load!

Then we'll see what new problems arise