Honeywell PA404 holding system off

Hitzkup

i would like to replace my pa404a pressuretrol with a vaporstat what model do i need?

mys

Henry_10

Honeywell PA404 holding system off

What I have is a single pipe, steam, millivolt system feeding a small apartment house of 5 floors. After being off all summer it didn't come on when it should have this weekend. The 2 year old Honeywell PA404 (not sure if is A or was holding it off. It was set at 3psi cut in with a 3 psi differential. The construction of the unit is like a see saw with the leading edge connected to a plunger type thingee that senses the pressure. The cut in spring tensioner controls the pressure on the back on the seesaw. If I push the plunger down the furnace comes on. If I crank up the cut in to 8 psi the furnace comes on. It seems to me that the cut in pressure really just senses the position of the plunger and when this is exceeded by movement the differential setting it cuts off. So the question is, can I just leave it at 8 psi? Seems to work all right there, but I know this is higher than recommended. On the other hand the boiler pressure guage never rises above 2 psi.

Thanks,

Henry

TGO_54

Henry,

> What I have is a single pipe, steam, millivolt

> system feeding a small apartment house of 5

> floors. After being off all summer it didn't

> come on when it should have this weekend. The 2

> year old Honeywell PA404 (not sure if is A or

> was holding it off. It was set at 3psi cut in

> with a 3 psi differential. The construction of

> the unit is like a see saw with the leading edge

> connected to a plunger type thingee that senses

> the pressure. The cut in spring tensioner

> controls the pressure on the back on the seesaw.

> If I push the plunger down the furnace comes on.

> If I crank up the cut in to 8 psi the furnace

> comes on. It seems to me that the cut in

> pressure really just senses the position of the

> plunger and when this is exceeded by movement the

> differential setting it cuts off. So the

> question is, can I just leave it at 8 psi? Seems

> to work all right there, but I know this is

> higher than recommended. On the other hand the

> boiler pressure guage never rises above 2

> psi.

>

> Thanks,

>

> Henry





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TGO_54

Henry,

You don't want to leave the control at 8psi.

Lower the operating side to 2 psi and set the diff at 1.5 psi.

When the t-stat calls for heat the boiler should fire and will continue to fire until the t-stat is satisfied or the boiler reaches 2 PSI. If the boiler cuts out on pressure (2PSI) it will stay off until the pressure drops to .5 PSI.

You may want to consider upgrading to control to a more sensitive type like a vaporstat.

If you have any doubts or if the adjustmants don't work - call a pro. There is a link on the upper left side of the screen to help you find one.


Good Luck

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Henry_10

I am having some trouble understanding this.
Are you saying that the circuit makes at the set point minus the differential ( 2 - 1.5 = .5 )?

That would make sense in that if both were set to 3 as I found them there would be no place below.

I thought from the directions that it would make below the set point ( 2 ) and break above (2 + 1.5 = 3).

Unknown

Henry

we had a bad run of PA404s a few years ago . The same symptoms that you're having - we would set the cut in at 2 and the diff at 1 . The burner would not kick on till we set the cut in around 4 or 5 . I would recommend upgrading to the mercury controlled pressuretrol or maybe a vaporstat . I'm sorry I don't have the model numbers though .

TGO_54

The circuit

breaks at the high setting. It re-makes at the limit minus the differential. If there were no differential, or if it is set too low the boiler will short cycle.

The 404 is not a very acccurate control, personaly I don't use them on my steam systems.

If you are not 100% sure of what you are doing, you may want to call in a pro to evalute your system.

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carol_3

Thanks for your help, on this, TGO and ron jr!

Kirk

pressuretrol

I have a similar situation .. I have followed all of the suggestions about lowering the setting on my PA404A1099 to .5 it might work for a day or a cycle or two then it needs to be adjusted up a 1/4 turn or so ...I hate to just set the thing at 2 or 4 or some higher setting than necessary ... but I hate waking up in the middle of the night cold becasue the unit decided it did not want to kick on ... besides just buying a better unit are there any solutions ?

Henry_10

pressuretrol info

Definitive information on these controllers can be found here:
http://customer.honeywell.com/Techlit/Pdf/60-0000s/60-2341.pdf
basically PA404A is also called PA404A1033 and seems to be a replacement for PA404A1099

PA404A exists in 2 types which one is stated inside the cover
additive- cuts out when outside control + inside wheel pressure is reached, cuts back in when drops below outside control
subtractive- cuts in at outside control - inside wheel pressure, cuts out at outside control

PA404B is a fan control

Hitzkup

vaporstat

i found the information on honeywell's website.

http--customer.honeywell.com-Techlit-Pdf-60-0000s-60-2158.pdf

mys

Joe_55

Vaporstat

you need an L408A-1157 available from state supply.com