Thermostat Placement in Apartment Building

ben_18

My question has a few parts.
Some background: I am dealing with a 5 story 15 unit apartment building in NYC. They are 2 and 3 bedrooms. Each apartment has 2 radiators about 45 EDR each and 3 bare 2" pipes 10 feet tall.
1)What thermostat system would you recommend for this building? It was running on a heat-timer and now I have installed a Honeywell Redlink with 2 remote temperature sensors. (I stopped using the heat timer because it didn't keep a consistent temperature, some days it was very hot inside and some very cold.)
I installed the two sensors for the Honewell in apartments on the third floor. It is set to 73 by day and 71 at night. In the morning the boiler is on from 5:30 am sometimes until 10 am to reach 73 degrees. And then goes off for 4 hours and on again. I would like it to cycle almost every hour to keep a more consistent temperature.
2)Where in the apartment would you locate the sensor. In a room with a radiator-and where in that room. Or in the hallway of the apartment away from the radiator.
I am monitoring the temperature in 1 apartment on each floor with the Wireless Tag brand sensors so i can see the temperature on each floor and when it goes on and off.

nicholas bonham-carter

I would install the Honeywell sensor in the top floor coolest apartment, and set the thermostat for a constant 67 degrees, with no setbacks. In the setup of the thermostat choose 1 CPH.
Use your wireless tags to see who may be overheating during this time. Studying the layout of the overheaters will show you where the main venting is inadequate. The desired result will be steam reaching all the rads on each floor simultaneously this is where you save money, and have happy tenants..
Since you have such a tall vertical height, you may benefit from having the main vents at the top of each riser.--NBC

Abracadabra

http://www.rdcontrolsystems.com/index.php

ben_18

@Hatterasguy what is the difference between a tekmar and a heat-timer they both seem to run on outside temperature.

@nicholas bonham-carter The problem with putting it in the top floor is that it seems the way the Honeywell works is that it turns the boiler on and waits for the temperature to be reached at the sensor and then stays on for a while after that. A sensor in the top floor will run for a long time until the temperature is reached there and then some. That is the problem I have now. It runs in the morning for 4 hours straight.
I'm thinking of putting it in the first floor in the room with the radiator and putting it pretty close to the radiator so that the boiler doesn't stay on for so long on each cycle.
I guess my question now is how close do you put the sensor next to the radiator?

@Abracadabra how does that use the outside temperature is it just like and outdoor reset or does it even have a role during normal operation. And are those sensors wired or wireless?

Abracadabra

ben said:

@Abracadabra how does that use the outside temperature is it just like and outdoor reset or does it even have a role during normal operation. And are those sensors wired or wireless?

Outside temperature is used to alter the inside temperature setpoint. It will also shutdown the system when outside temperature is over a set point you create.

They offer wired and wireless. Wireless have batteries that last 3-4 years. Very good range on the wireless setup.

nicholas bonham-carter

The thermostat anticipates how long the boiler must run to get to the set point, as the radiators retain heat after the boiler shuts down. The area the sensor is in will maintain the set point with complete accuracy, and no overshoot.
Your job is to make sure all the building behaves like the sensor area.
Putting the sensor in a cooler area makes sure it reacts quickly to plunging outside temperature. Your venting is the key to an even temperature throughout the building.--NBC

aircooled81

Just interested, system type - 1 pipe or 2 pipe no control valves on rads?
I'm just interested, if you have any pictures of your system, or a little detail how it works.
We dont have many high rises out here with steam radiators.
I'd love to know what the 3 2" pipes are for.

nicholas bonham-carter

In an earlier post, I believe the OP said the system was a one-pipe, and the risers took care of the 3 bathrooms on each floor, all stacked one on top of the other for the 5 floors.
In this sort of tall and narrow building, the risers probably need main venting as well as the mains in the basement. This will make sure all risers, and rads fill with steam at the same time.
If you get a call on a system with an old heatimer control, look for basic causes of imbalance, such as inadequate main venting, for which the heatimer was meant to compensate for.
Down in the Caribbean I saw a magnificent sail boat, named "change order", and I think there is another sister ship, called "heatimer"!--NBC

ben_18

@nicholas bonham-carter I have a Honeywell at home and in a 4 unit building and goes on almost every hour for some time. In this building the Honeywell goes on for 4 hours in the morning just to raise the temperature by 1 degree. There is something wrong with that. All thermostats are set to 1 CPH.
@aircooled81 There are 3 bare pipes in each apartment for heat besides for the 2 radiators there are 5-6 rooms in each apartment. It is a 1-pipe system with a 50HP steel tube boiler.

nicholas bonham-carter

Yes very wrong. Leave the temperature constant, with no off periods. If you were driving a car on a long trip, would you constantly vary the speed, and even turn off the engine at times? The best fuel consumption would be had by using cruise control with a constant speed.
Any bad main venting in the building is like dragging brakes, making your fuel supplier rub his hands with glee over the extra fuel he can sell to force the air out of the system through constipated little radiator vents. The tenants will however be rubbing their hands trying to keep warm in some parts of the building, and opening windows to cool off in others.
Your building is large, and all the air, and structure have to be warmed up to the new temperature setting after these setbacks. When the building was first built, the variations of temperature you describe would not have been tolerated from any steam professional installing a system. Nor would fuel inefficiency be permitted, as it is not a recent concern.
The setting 1 CPH is somewhat of a misnomer, as it refers to the control anticipation setting of the thermostat, rather than simply some built in timer.
If you don't already have a copy of the steam books for sale in the shop here, then order them and read them. After you have followed the advice inside, they will have been paid for by a few days of fuel savings.--NBC

ben_18

@nicholas bonham-carter I will try keeping it at one temperature. I just looked at it and it was reading 75 degrees even though it was set at 73! It overshot by a lot and that is the problem I am having. I think part of the reason is sensor placement.

KC_Jones

Have you already balanced the venting on the system? Gotten your main venting taken care of and adequate? Are all the rads in the building getting steam at about the same time? There isn't a boiler control that will compensate for temperature variation in the building, that is done with proper venting. I don't know the heat timer, but as far as I know these outdoor reset controls will set cycle times like you want to do. The thermostat isn't capable of this. I fear you may have abandoned a control that does what you want and just needed adjusting in favor of one that doesn't do what you want. I also wonder as NBC eluded to if your venting is proper.

ben_18

Full disclosure: there are no main vents!
However, using the wireless tags it seems that the steam reaches all floors within 5 minutes of each other

nicholas bonham-carter

If you had main vents, the steam should take 3 minutes to get to all the radiators at the same time.
That probably equates to several hours a week of fuel waste. I know that oil and gas are at their lowest prices now, but will not always be so cheap.
Not only is there the problem of fuel waste, but some of your tenants will get 5 minutes more heating, in recovery mode than others, and who will like that?--NBC

aircooled81

Gentleman, thank you for your replies, i was hoping i would hear more today when i got home from work
So, NBC, when you approach a building to determine if main venting is addequate, do you start from top to bottom? Do you find main vents pull them off and test them? Are there a hellaof lot of options to vary the amount, or are there just a few standard sizes?
Basically, how do you identify the need for mor or better main air vents?

And like an example with this building, would you expermient with sizes since it has none, or is there a rule of thumb?

BobC

The gist is to vent the mains fast and the radiators slowly. That way steam should get to all the radiators at about the same time.

Trying to balance a system before the mains venting is good is usually a exercize in futility.

Bob

Fred

For Main venting, if you measure the length of each Main and tell us that length (of eac) and the size of the pipe, we can tell you how many and what type vents to install. They are typically installed at the end of the Main, after the last radiator run-out. While you're surveying the mains, look for any place that has a plug in it that might make it easier to install the vents. On a building that size, you will likely need multipe vents, installed on an antler. Hopefully there is a convenient place to install it. If there is no good place at the end of the Main, look and see if there is any place on the Dry returns where they can be installed.
On the risers, estimate the length of the risers and the pipe size as well. They will likely need some venting at the top of those.
A rule of thumb, at least for starters is the equalivent of one Gorton #2 vent for every 20 ft. of 2 inch pipe but that may be adjustable a little. At this point, any main venting will help a lot.

gennady

No thermostat can to control building this size. No matter how many sensors you will stick in there.

There is no difference between tekmar and heat-timer. same principle of operation.

If outdoor reset control did not work, then it was not set up properly, or sensors location was wrong. It would be better to correct mistakes of setup and/or installation, than replace one mistake with another one.

Or maybe you had some other issues not related to heat-timer at all.

ben_18

Just an update: I have two remote sensors in the building now and the thermostat is set at hold 72 as suggested by @nicholas bonham-carter and when it is cold outside it goes on about once an hour, the way I want it to. None of those long 6 hours cycles I used to have in the morning. Thanks for the advice

nicholas bonham-carter

Don't forget the main vents.--NBC