old honeywell 2" valve actuator failed partially open

bkc

Hi,

I went to church today and discovered its a very warm 77 in half of the building.

It appears that a honeywell valve actuator is stuck partially open. The valve is located over the boiler next to the main riser, its pretty difficult to reach w/o getting burned. I was able to close the service valve.

Can anyone identify the model of this actuator so I can get the specs on it before troubleshooting? Also, is this a 2" globe valve?

The wiring is quite a mess. The valve is controlled by a single thermostat that is receiving 24VAC (checked w/ meter). I tapped on the relay and I can see it spark inside, so I think power is also flowing to the actuator. I didn't have time this morning to try routing around the relay to power the actuator to open.

Typically the needle indicator is either at the 6 or 9 position, but now its stuck at 8 o'clock.


2 years ago I replaced a broken actuator on a 1.5" line with a Honeywell ML6984A4000 non-spring return valve actuator. I wonder if a similar/same actuator can be used on this valve with the appropriate adapter.

Thanks

--

Stuck at 8



Typical max open position



Valve



Actuator bottom view



Actuator side view



Relay wiring


Relay

JUGHNE

How many zones/tstats do you have in the church?
Do you run a "hot" boiler for the season?

bkc

Hi,

There are 6 zones in the building.

By "hot", if you mean does the boiler run all heating season, yes it does. Regardless of demand, once the boiler is on it will maintain 1/2 to 2.5 lbs psi (that's the lowest I can get the pressuretrol to go)

We have a Weil Mclain LGB-8 22 HP boiler.

JUGHNE

I had that in a school house with 2 zones.
I did add relays that would only fire the boiler is a zone opened.
You could just perhaps put an outdoor tstat to keep the boiler off until temp dropped to the magic point of maybe 50-60 degrees.

That is a lot of boiler to run if only 1 zone opening, probably short cycling?

Jamie Hall

Oy. Well, no particular comment on the actuator -- it does look stuck. However, you might be able to rethink the control on that boiler to save your church a good bit of money, if perhaps not being quite as comfortable. The idea would be to run the boiler only for a specified fraction of the time, with the fraction -- and the length of burn time -- varying at least with the season or, in a more sophisticated way, with the outside air temperature. What I'm thinking of is having it run long enough at any one time to ensure that all the radiation can get up to temperature and the boiler up to its shutoff -- and then turning it off and forcing a time delay until the next on cycle. A longer time delay when it is warm out, and a shorter one when it is cold.

It would need some experimentation to determine the best length of on time -- that would vary with the kind of radiation you have (radiators? Fin tubes? indirect convectors?).

@PMJ may see this, and he has done a good deal of work with that type of control quite successfully.

EBEBRATT-Ed

@bkc take the 4 screws out of the actuator cover you will find the model # of the actuator there. Also The packing looks like it's leaking so that should be rebuilt. Yes it is a Honeywell globe valve


I am guessing the relay pulls in from the thermostat and opens the valve. When the stat opens the relay deops out and the NC contacts in the relay drives the valve closed.

R on the actuator is 24 volt power. R-B (Red -Blue for BTU) usually opens the valve But not always and R_W (Red -W closes the valve. The other wire could be and end switch to start the boiler

bkc

Thank you all for your comments. @EBEBRATT-Ed We're expect a cold-snap tonight (-11 F). I'll try to get back to this on Thursday when it warms a little, since I need to shut off the boiler for a few hours to safely reach the valve. Hopefully there is enough space between the top of the actuator and the ceiling to get the cover off.

I'm also interested in energy savings, I guess a 'boiler burner set-back' of some kind. Can cycling the boiler temp cause problems, e.g. expansion/contraction fatigue?

Jamie Hall

A steam boiler will always operate at the same temperature, so that's not a problem.

The biggest problem is that a steam boiler really needs to be matched to the size of the system it's powering, or to be controlled so that at least its average output is matched. On a system with multiple zones, any combination of which can be controlling at any time, this gets to be ... interesting.

Traditionally steam boilers in smaller sizes -- and in the grand scheme of things, this is smaller -- were controlled on pressure. This works quite well if the load isn't variable much, and if the boiler is reasonably well matched to the load. On systems with multiple zones, particularly if the radiation is suitable (fairly heavy) There are better ways to do it. Most of them involve using a combination of a timer and a sensor to make sure that steam has gotten around the system where needed, and then letting the boiler run for a set time depending on outside temperature. You might try contacting @PMJ . He's an amateur, but has some good and simple innovative approaches. Tell him I sent you.

PMJ

Not sure I would have much to offer here.

If there are known long periods where no steam is needed like on my 200HP process system we have a single manual switch to aquastat control in series with the pressure control which idles the boiler at just below steaming temperature. That boiler is in a basement and it only takes about 6 minutes of burn time on low fire every 12 hours to keep it at 180-200F. Better for it to keep it hot and doesn't cost much.

In the case here might any zone be needing steam at any moment 24/7? If so and everyone is used to the instant response of pressure steam always available it would need to be discussed first if any reduction in response time at all was acceptable to pursue the possible savings of not always maintaining pressure.

mattmia2

Doesn't heattimer's control fire the boiler based on when steam gets to the end of the main and outdoor temp?

Jamie Hall

mattmia2 said:

Doesn't heattimer's control fire the boiler based on when steam gets to the end of the main and outdoor temp?

I think so -- I think it starts counting down, based on outdoor temperature, from when steam gets to the farthest reaches. Kind of thing I was thinking about.

The Steam Whisperer

Any kind of outdoor reset timer won't work well if you are setting back temperatures when the building is unoccuppied....there won't be enough on time to recover the building. You can probably take another one of the contacts on the control relay to fire the boiler only on call for heat. This will keep the boiler off when heat is not needed, but give you full capacity when you need to recover the building temperatures. The recommended set back temperature for religous structures when not in use is 45F in order to keep the relative humidity high to prevent damage to natural materials ( like a pipe organ, pews etc.) but still keep the wall above freezing to protect the plaster. This setback would be for several days or more between uses.
From 1978 to 2020, my church used a 7 day timeclock to turn on the boiler for building usage and then a freeze protection stat set at 45F wired in parallel with the timeclock to fired the boiler when it got cold enough to need minimal heating. That setup cut fuel bills about 1/3 over leaving the boiler operate on pressure all winter.

The LGB also has high/ low firing so adding a pressuretrol to cut out high fire when pressure builds can be helpful too. It only takes about 375,000 btu/hr input to keep our 15,000 sq ft building at setback temperature down to about -7F with wind. We have a 250 seat sanctuary as part of the complex which is about 50 feet at the peak built in the 1930's so no insulation.