Honeywell CT87K stat - cph setting???

Patchogue Phil_2

Honeywell newer round CT87K heat-only thermostat, ancient propane Hydrotherm boiler.

How does this thermostat control/affect cycles per hour? (I know where the dip switches are located). I am curious about the mechanics of this function.

Also ... I know longer burn times are generally more fuel efficient. Does a lower cph relate to longer burn times? The Honeywell directions say this stat connected to a gas boiler (not a 90%-plus efficiency) should be set to 3 cph. Would a higher cph give better consistent perceived comfort level by keeping the high/low of room temps much closer to thermostat setting?

This stat is in my 79 yr old moms house. She keeps using the stat as an ON-OFF switch. When she feels cold she cranks the stat higher. When she thinks she's warm enough she lowers the stat 10 degrees. Then the cycle repeats. I'm trying to get her to leave the stat alone. Was wondering if a higher cph would help (her), but without any real adverse effects to the boiler.

Note that a digital &/or programmable thermostat is unwanted by mom.

vaporvac

I assume this is water, not steam? I think 2 or three is recommended for water, but more will even out the temp, although after a point it will decrease efficiency. This is my understanding of it, but I have steam and a digital Tstat. I think these older types have an anticipator that you can mess around with to gain tighter control on temp swings. We've had a lot of posts on this this past winter. Hopefully, someone else will join in.

Patchogue Phil_2

Yes hot water, finned baseboard. Unless I missed it, I didnt see an anticipator like on the original old style round dual thermostat.

Jamie Hall

It will probably work best on 3, all things considered. That thermostat is actually a digital thermostat -- just in a round housing which looks a lot like the older T87s, which were analogue.

An anticipator is in the analogue types -- what it actually is is a small (very small!) heater which fools the thermostat coil -- a bimetal -- into thinking that it's warmer than it really is, and thus shutting the thing off sooner, and then the system catches up. Adjusted properly, they work wonderfully well. They can be rather fiddly...

The digitals don't have that at all.

Both you and your mom will be happier if she leaves it alone. I don't see that happening!

Patchogue Phil_2

Yeah , last night about 900pm I had to drive half an hour to her house cause the heat wouldn't stop running. House was 84°F. She spun the thermostat housing mount out of level. While tilted, it kept calling for heat. Tightened the screws & added another screw.

House overnight cooled down to 76°F while tstat set to 70. Still, mom was compelled to lower setting to 60 just in case. ::sigh::

Maybe I should install one of those locking clear boxes over the tstat. ;-)

Fred

Don't take away one of the few vices she still has. Just make sure it's good and tight to the wall. It might be good if there is some way you could peg it (with some kind of stop) so that it can only be turned a specific range, say 65 to 75. Maybe they make a specialty thermostat with a fixed range???

Patchogue Phil_2

Please! I had to remove the former , nice digital programmable tstat, and put in this simple dial tstat. If I somehow put in a mechanical stop on this tstat, she will twist the stat off the wall!

vaporvac

Maybe you could put in another remote wifi Tstat that YOU could control, and disconnect this one, but leave it up, just not working. Deceitful, but she could still have fun with it.

Patchogue Phil_2

Kinda like a baby's "Busy box" toy! But for seniors!

Harvey Ramer

This reminds me of a story about my parents. They had a wood stove for heating, their whole life. So they are getting older and I put in a ductless heat pump for them. I show them how to run it and off I go. A few days later, I stop in to check up. There is the unit running full bore and right beside it the door partly open. I said, Why do you have the door open? They said, well it was a little warm in here so we opened it a bit. I said, no no no, we don't do it like that anymore. If you are to warm, just set the temperature on the ductless to a lower setting.

It took a while for them to come around.

BobC

@vaporvac back when the first oil shock hit in the early 70's my boss told me to buy and install setback thermostats to cut fuel costs. The plant was 200 X 100 two floors with hanging forced air furnaces.

i bought a couple of setback thermostats from Grainger and then found out of the way places to install them. I left the old round Honywells on the wall so people could adjust them as they liked.

Then I had to fight with the boss to bring up the heat early so the plant would be reasonable when folks arrived for work. I found the best course of action was to agree with his reasoning and then do what i had to behind his back. As long as fuel usage went down I knew he wouldn't look to closely.

It's often easier to beg for forgiveness than ask for permission. Sometimes you just have to protect people against themselves, that was true in the military as well.


In this case the scheme won't work because that old girl sounds like the type who would move heaven and earth to get what she wants. One thing that might work is to put a high limit thermostat somewhere that is set to 75 or so, that gives her control but limits the damage.

Bob

nicholas bonham-carter

A honetwell visionpro, with remote sensor, (placed next to the original thermostat), would enable her to have her busy box, and yet have sensible control over the heat for you alone to adjust!--NBC

unclejohn

I have installed digital T'stats sideways and they work fine. If the house over shot that much some else is wrong. Maybe your mom is right and it's not working properly.

JUGHNE

Twisted out of level should not affect the digital t-stat. Unless it moved the indicator arrow out of wack enough to add to the confusion.

I would second the remote sensor with real T-stat elsewhere. You can even get wireless everything with internet monitoring and control for you to work with. (but you probably go there often anyway)

I had a customer with Heat Pump older t-stat with levers above & below stat. For him the solution was brad sized nails (from electric cable staples) driven into the wood paneling to keep him from placing the fan in "auto" or the system switch in "Emg Heat". Also nail stops for high temp and low temp. He would not "over ride " the nails but just knew that those were off limits.
Probably won't work for your situation....went thru the same thing with our mother.

It is possible that something on the boiler end of things is sticking on or off and slow to respond. The remote T-stat would help you identify that if so.

SWEI

The controls industry sometimes uses the term "secretary stat" for this.

With DDC, we can manipulate the UI so the customer sees whatever they need to see. What goes on underneath is up to us to decide.

Patchogue Phil_2

unclejohn said:

I have installed digital T'stats sideways and they work fine. If the house over shot that much some else is wrong. Maybe your mom is right and it's not working properly.

If this round CT87K t-stat does NOT need to be level to work correctly (like the mercury switch older versions), then I don't know what was wrong. Perhaps twisting the mounting plate made the 2 wires short out. I did not see any nicks on the visible part of the wires, but it is possible the wires are nicked inside the wall near the stat.

I just learned from googling, that there is an internal button-battery inside this model. Not clear on how this stat would perform if the battery is low or dead. I do know mom turns off the emergency switch during June thru Oct.

Mad Dog_2

I recently had two T- 87s. Bad right outta the box. Bought second one for stock. Late at night...from the big box store. Mad Dog

Patchogue Phil_2

Been reading online that many of these newer non-mercury T-87s are bad out of box. Either they don't switch the heat ON unless turned 10 degrees higher than desired, or they don't shut down call for heat. Ugh.

This one is working OK the last 3 days, but I'm gonna change it. Also have to work on Mom to get a new boiler. This one is from circa 1970s (Hydrotherm HC-100) - but that's another story thread !!!! :-)

Patchogue Phil_2

This evening, Mom says temp in house up to 76, when she had thermostat set to 70. Baseboards are all hot, so it's not solar heat gain.

She turned off the emergency switch and opened windows.

I'll have to replace the thermostat.

Fred

Patchogue Phil said:

This evening, Mom says temp in house up to 76, when she had thermostat set to 70. Baseboards are all hot, so it's not solar heat gain.



She turned off the emergency switch and opened windows.



I'll have to replace the thermostat.

Mom may be old but she probably knows what she is talking about and probably has a very good reason for always fidgeting with that thermostat.

RobG

Patchogue Phil said:

Been reading online that many of these newer non-mercury T-87s are bad out of box. Either they don't switch the heat ON unless turned 10 degrees higher than desired, or they don't shut down call for heat. Ugh.

This one is working OK the last 3 days, but I'm gonna change it. Also have to work on Mom to get a new boiler. This one is from circa 1970s (Hydrotherm HC-100) - but that's another story thread !!!! :-)

At your moms age you should probably keep the old HydroTherm boiler. The HC series was a workhorse. The name HydroTherm sends shivers down most peoples spine. That is due to the Pulse boiler, not the HC's. If it's not leaking I would keep it. She will never get the payback on a new boiler. Just service it regularly.

Patchogue Phil_2

>>>> Rob: just service it regularly.

Rob, what's there to actually service? Besides keeping cobwebs out of the air shutter area, what else should be done?

To me it looks like a big square castiron "tray" of burner flame ports like a propane BBQ under a ribbed/finned iron pot of water. I've never taken the flue off the top but from what I can see peering upward from down low there is no soot. But I cannot see very far upwards.

I don't know what EXACTLY the propane company tech did last time it was serviced (a few years ago when it needed a thermo couple) but they "cleaned it". I wasn't present at the time.

RobG

That boiler has a horizontal stacked heat exchanger. To service it the it the flue needs to be removed and the dome removed, brush flue passages, remove burners and tray, clean and vacuum out, inspect flue and chimney. Put it back together and do combustion analysis. Presto!

Patchogue Phil_2

Getting back to my original query.....

>>>How does this thermostat control/affect cycles per hour? (I know where the dip switches are located). I am curious about the mechanics of this function.


How does the cph get regulated? Does the thermostat actually keep an internal timer and counter to limit how many times in an hour the circulators will be allowed to run?