Pressuretrol shot, it looks

Hen

Hello,  Pressuretrol on my residential boiler seems shot.  I have it set at cut-in of 0.5 and differential of 1, so it should cut out at about 1.5 psi.  I just changed the pigtail and have a Wika low pressure gauge.  The system starts making steam in 10 minutes or so and boiler stays working at about 0.5 psi for some 45 minutes, at which point the pressure starts climbing to 4 psi.  At that point it begins short cycling between 3 and 4 psi.

I test and observe the boiler by shorting thermostat wires at the boiler.

Am I correct that the pressuretrol looks shot?  What is the source to purchase Vaporstat?  Thank you.

crash2009

Vaporstat link

L408J-1009  I got a pretty good price here.

http://www.energyequipment.com/searchdbs.aspx

BobC

Spring for a vaporstat

Pressuretrols are variable as hell and it gets worse with age.



If your going to have to replace it, consider going with a 0-4PSI vaporstat. It will cost at least twice what a pressuretrol will but it gives very good control down to 10-12 oz. If you want pressure control below that you need the 16oz model but that usually just for true vapor systems.



You can use the pressuretrol for an emergency backup to the vaporstat for another layer of safety. If you do that I would advise putting it on a separate pigtail so you don't have all your eggs in one basket.



Bob

Charlie from wmass

are you sure the pig tail is clear into

the boiler? I have seen where the piping between the pigtail and boiler was clogged or even the bushing in the boiler was clogged.

Hen

Pigtail is brand new

The brass pigtail is brand new, just installed, directly into the LWCO; all the fittings are new brass; the old pressuretrol sits directly above the pigtail on a nipple; there is a new brass tee between the pigtail and the 'pressuretrol nipple'. Low pressure, new Wica gauge is connected to the tee. The Wica gauge is pretty consistent with the readings  on the old 0-30 psi gauge.

BobC

One more thing

If you look up into the bottom brass fitting on the pressuretrol you will see a very small hole. If that hole has any crap in it the pressuretrol is not going to work right. Not probable but definitely possible. If it's not that then you need to replace the pressuretrol.



Bob

Charlie from wmass

just saw one yesterday

where the old pressuretrol that was installed by a "pro" was clogged with Teflon and pipe dope. On my own ancient beast the nipple had a scale layer over the inside of the LWCO on the boiler. I guess after 60 years it needed cleaned finally.

crash2009

Sounds like

the old pressuretrol is not all-together shot.  Its just that it doesn't do anything until the pressure gets up to 3 or 4 psi.  The indicator and the actual pressure it shuts down the boiler are not the same.  As long as it shuts the boiler down at the same psi every time, it still works.  You might want to keep it, and install it as a secondary, and get a vaporstat to use as your primary.



When you were watching the 0-3psi gauge, the first 10 minutes were likely pretty much uneventfull, then, all of a sudden the pressure went up to 3 or 4 psi.  I realize that you cant be 2 places at the same time but you need to figure out which rad is your "last rad" (the last one to fill up with steam).  When the last rad fills up, and the air vent closes, write down the pressure reading on your 0-3psi.  This number that you wrote down is the number you want to set your vaporstat to.  This will shut down the boiler just after the last rad is full, and you will save a bunch of fuel dollars.  Once all the rads in the house are full, the boiler doesn't need to be running anymore.

The reason why we suggested to keep the old pressuretrol, is lets just say "sometime in the future" the vaporstat fails to work and the pressure continues to rise, the pressuretrol will catch it at 3 or 4 psi.

I may not be exactly right about the vaporstat and the last rad, but that will get you close.

In my attached February 23 notes you can see that I wasted a bit of fuel that day. 

At 553 my pressure rose 1.5 ounces.  That is where I should have shut down, my last rad was near full.

At 554 my pressure rose 3 ounces.  Pressure shoots up fast after last rad is full.  After the last rad is full, it can't get any fuller.  All you get is more pressure, which is hard on the equiptment.

At 556 I ran out of water.  

crash2009

Looks like

I am contradicting you guys.  I was writing a long one while you were posting.  No contradiction intended.

Hen

Vaporstat ordered from Pexsupply

Hello All.  Thank you much for the suggestions / recommendations.  Vaporstat should arrive in couple of days. I will try to establish the pressure at which last rad is full.  Will keep the pressuretrol as a back up. HOW SHOULD THE PRESSURETROL and THE VAPORSTAT BE WIRED? The pinhole on bottom of pressuretrol looked clear last I checked, but will take another look. The LWCO is about one year old. Will check the hole again, where the pigtail is mounted on LWCO. (By the way, the boiler is about 25 yrs old). As I wrote in my initial post, the boiler starts making steam in about 10 minutes at which poit pressure on Wica goes to 0.5 psi and stays like that for about 45 minutes. After 45  minutes of non-stop operation the pressure starts climbing and by 60 minutes it is at 4 psi. This is where the boiler starts short-cycling, like 1-2 minute intervals, between 3 and 4 psi.  This is also the time, where I start hearing some water hammers upstairs.  I presume the steam is trying to go up and is competing  with the drainage water. Thank you All.

BobC

Wire in series

Wire them in series, the higher pressure pressuretrol will not open the circuit unless the lower pressure vaporstat fails to open.



Bob

Hen

Wiring Vaporstat and pressuretrol IN SERIES hookup

Hello.  I installed Vaporstat recently in  place of pressuretrol. Seems to work great. Now, I would like to reinstall the pressuretrol as a back-up alongside the Vaporstat. I understand it needs to be wired in series, but the terminals on my pressuretrol are identical and unmarked. Both wires that were hooked up to the  pressuretrol prior are black. SO, where do I physically connect the existing two black wires and how do I connect the Vaporstat and Pressuretrol together.  Thank you.

crash2009

Series

To wire the pressuretrol and vaporstat together in series you need 3 wires, lets name them 1, 2, and 3.  1 and 2 are the two black wires you have and 3 is a wire you have to make.  1 goes to the pressuretrol.  2 goes to the vaporstat.  and 3 goes from the pressuretrol to the vaporstat.

Hen

Vaporstat / Pressuretrol series hook-up..the terminals

Hi. Which terminal screws on the Vaporstat and on the Pressuretrol do I connect with wire # 3? Or, being that the devices are really 'only'  ON/OFF switches that close or open the circuit, it won't matter. (?) 

Currently the Vaporstat is hooked up with one 'old' black wire to terminal R and the second 'old' black wire to terminal B.  Thank you.

Steamhead

First of all

is this 120-volt or 24-volt wiring? 

Hen

24 volt wiring

It is 24 Volt wiring. Tx.

Steamhead

OK

the terminals on the old Pressuretrol are interchangeable. It doesn't matter which wire goes to which terminal.



Use a 2-wire thermostat cable for neatness. Run the cable from the Pressuretrol to the Vaporstat, with the two wires connected to the two Pressuretrol terminals.



Now disconnect one wire from the Vaporstat, but leave the other one connected. For clarity we'll disconnect the one that goes to terminal R. Connect one wire of the Pressuretrol-to-Vaporstat cable you just installed, to the R terminal on the Vaporstat. Connect the other to the wire you previously disconnected from R, using a wire nut.



Now the 24 volts must flow thru both the Vaporstat and the Pressuretrol to allow the burner to operate.

Hen

Vaporstat terminals -- interchangable or not

Are the R and B terminals on the Vaporstat interchangable as well??  No?  Sometimes yes and sometimes no?  TY.

Steamhead

In this application

they are, but that might not be true elsewhere. 

Hen

W terminal on the Vaporstat

I am only using the R and B terminals, but what is the purpose of the W terminal on  the Vaporstat?  Do the letters R, B and W stand for red, black white, electrical color coding? As in hot, hot, neutral (return)? TY

There is another terminal-like screw to the left of the R W B terminals, is that a ground screw? TY

Steamhead

The W

is for a system where you want to turn something ON, rather than OFF, when the pressure rises. Obviously we aren't doing that on your boiler.



And the letters could certainly be used with a color-coded cable if desired.