Relay for 24V Thermostat on 120V system

ben_18

I would like to replace a Heat Timer which runs on 120VAC with a new Honeywell thermostat that runs on 24VAC. This is in a small apartment building and it is a 50HP steel tube boiler with a Webster JB1-07 burner webster-engineering.com/product.php?id=8. What relay should I use to run the thermostat?

Abracadabra

When needed on my boiler installs I use the honeywell.

http://www.supplyhouse.com/Honeywell-R8845U1003-Universal-Switching-Relay-w-Internal-Transformer-11013000-p

SWEI

Is the Heat-Timer actually timing boiler cycles? If so, are you sure you want to lose that?

ben_18

Thanks @Abracadabra and @SWEI @Hatterasguy these look like the right type.

ben_18

SWEI said:

Is the Heat-Timer actually timing boiler cycles? If so, are you sure you want to lose that?

It's not working correctly, that is the problem. The average temperature is 76 degrees in the apartments and that is even after lowering the setting on the heat timer. I am monitoring every floor with wirelesstag.net/index.html and one floor is 80 two are 76 and one is 70 so the heat timer is not working and wasting a lot of fuel. I just wanted to give a shout out to the wireless tag temperature sensors. It has a great app. I plan on using them with a Honeywell red link thermostat and I can even use the wireless tag sensors that i have already installed as a remote sensor for the Honeywell thermostat.

wogpa67

Why not go with net metering and charge the tenants for usage?

Abracadabra

ben said:

I am monitoring every floor with wirelesstag.net/index.html and one floor is 80 two are 76 and one is 70 so the heat timer is not working and wasting a lot of fuel. I just wanted to give a shout out to the wireless tag temperature sensors. It has a great app. I plan on using them with a Honeywell red link thermostat and I can even use the wireless tag sensors that i have already installed as a remote sensor for the Honeywell thermostat.

wireless tags are great. I've been able to use them to help balance large apartment buildings easily. incorporate IFTTT with wireless tags and you've got a powerful combination to do a lot of things.

nicholas bonham-carter

Is this one pipe or two?
i suspect these heat timers are often installed as a bandaid for an unbalanced system.
If this system is poorly vented, or over pressured, you may have the same uneveness of temperature, until you fix the problem.--NBC

doughess

Rather than focusing on what type relay, first determine what starts the system for heat. Is the thermostat going to start the boiler burner or a circulator system. Many installations have both 120 VAC and 24 VAC controls. If it has 24 VAC then the thermostat can activate it directly.

Most burner have start circuits that draw little current and the relay in most thermostats can handle it.

The classic self contained basic relay is the Honeywll RA89 series. You can tap the transformer in it for 24 VAC to run the thermostat.

nicholas bonham-carter

We would love to hear the outcome of this changeover.
It sounds like a main venting problem with such a range of different temperatures.
Are the temperatures at least consistent throughout each floor? I suspect the floors are hottest lower, and cooler higher, therefore needing some riser venting.--NBC

vr608

ben said:

SWEI said:

Is the Heat-Timer actually timing boiler cycles? If so, are you sure you want to lose that?

It's not working correctly, that is the problem. The average temperature is 76 degrees in the apartments and that is even after lowering the setting on the heat timer. I am monitoring every floor with wirelesstag.net/index.html and one floor is 80 two are 76 and one is 70 so the heat timer is not working and wasting a lot of fuel. I just wanted to give a shout out to the wireless tag temperature sensors. It has a great app. I plan on using them with a Honeywell red link thermostat and I can even use the wireless tag sensors that i have already installed as a remote sensor for the Honeywell thermostat.

Curious; these tags support Redlink?

Abracadabra

vr608 said:

ben said:

SWEI said:

Is the Heat-Timer actually timing boiler cycles? If so, are you sure you want to lose that?

It's not working correctly, that is the problem. The average temperature is 76 degrees in the apartments and that is even after lowering the setting on the heat timer. I am monitoring every floor with wirelesstag.net/index.html and one floor is 80 two are 76 and one is 70 so the heat timer is not working and wasting a lot of fuel. I just wanted to give a shout out to the wireless tag temperature sensors. It has a great app. I plan on using them with a Honeywell red link thermostat and I can even use the wireless tag sensors that i have already installed as a remote sensor for the Honeywell thermostat.

Curious; these tags support Redlink?

Don't think so. I think honeywell has an API for redlink, so you'd have to create some homebrew solution to link to the wireless tags. There's been requests to add redlink to IFTTT which would make it easier for many to connect the wireless tags to redlink but nothing yet.

nicholas bonham-carter

I see the OP has quite a bit on his hands (Redlink, venting), before he is able to reply to us about the outcome.--NBC

ben_18

@vr608 These tags do work in a limited way with redlink. You can link the honeywell to the Wireless tag account and it will log the temperature every 4 hours or so. It can also turn on and off the thermostat based on some even such as a window opening or closing.

@nicholas bonham-carter The heating system is one-pipe. The problem is that it is oversized for the building by around 50% or more. It short cycles. My question is will main vents stop it from short cycling if the boiler is so oversized?

@Abracadabra I bought the honeywell relay. I assume that the boiler 120V control wiring goes to the NO and COM connections on the board. Does it matter which wire is connected to the N.O or the COM connection? Also do you need power on L1 and L2 for the relays to work or do you only need the 24V connections from the thermostat to power the relay?

nicholas bonham-carter

Main venting will reduce the short cycling during the venting phase of operation. This is the time the steam is pushing the air out of the main pipes. The radiator vents cannot handle this job.
Measure the total length and diameter of the supplies, and dry returns, and we can suggest what you need.
After that, you may need Hoffman #40's on the radiators, with slightly larger vents on the top floor.
The desired result of a balanced system is steam hitting the radiators all at the same time, which you apparently do not have now.
The Honeywell Visionpro thermostat can monitor and control the boile from a remote sensor, which can be placed in the coldest corner of the building, or you can use an EcoSteam controller to run the boiler based on outside temperature. It will only work properly when the system is perfectly balanced.--NBC

Abracadabra

ben said:

@Abracadabra I bought the honeywell relay. I assume that the boiler 120V control wiring goes to the NO and COM connections on the board. Does it matter which wire is connected to the N.O or the COM connection? Also do you need power on L1 and L2 for the relays to work or do you only need the 24V connections from the thermostat to power the relay?

Just check the install instructions. You should just switch the hot and connected the neutral directly. Yes.. you need L1 and L2 powered to get the relays to work. This relay has an internal transformer. There's a schematic provided with the relay. This relay will also allow you to use a thermostat that requires a C connection.

vr608

ben said:

@vr608 These tags do work in a limited way with redlink. You can link the honeywell to the Wireless tag account and it will log the temperature every 4 hours or so. It can also turn on and off the thermostat based on some even such as a window opening or closing.

Thanks for the update Ben. I am curious how the linkage works; I'm in the middle of a homegrown outdoor reset project and I've found that my VisionPro doesn't report fractional temperatures, making it difficult to determine the actual indoor temperature vs what is displayed. Do the wireless tags show decimals in the recorded temperature, ie 70.1 vs 70? From the website it would appear they do but I just want to be sure before I shell out even more money for this project ;-)

ben_18

The wirelesstag do show decimal if you get the more accurate tags i think they are 13-bit. They don't really work well to control the RedLink thermostat-they only can turn it on or off. I use them separately to make sure every floor is getting heat and to figure out what temperature to set the honeywell at.

ben_18

Just an update I have installed the relay with the honeywell and they have been working so far thanks for your help. The temperature are a little more even with the 2nd floor at 78-80 and the top at 68-70. Before the top was 70-72 and the 2nd floor was 80-83. I don't think the heat -timer was good for this steam system. It goes on every hour for a certain amount of time depending on the outside temeperature. heat-timer.com/epu-epu-ch/
With the honeywell the steam goes on for longer less times a day and this heats up the upper floors more.
This is the temperature for the last 24 hours and there is a sensor on each floor. I could see every time the heat went on and off.
At night the third floor is set at 71 and by day 73

Abracadabra

Use slower vents on apt 22, and 43. Looks like you might have some air infiltration issues with apt 53B or it's over some unconditioned space.

ben_18

Abracadabra said:

Use slower vents on apt 22, and 43. Looks like you might have some air infiltration issues with apt 53B or it's over some unconditioned space.

Yes, however there are no main vents. I was thinking that it was venting through the first and second floor vents so I dont want to change them to throw off the whole system.

Abracadabra

ben said:

Abracadabra said:

Use slower vents on apt 22, and 43. Looks like you might have some air infiltration issues with apt 53B or it's over some unconditioned space.

Yes, however there are no main vents. I was thinking that it was venting through the first and second floor vents so I dont want to change them to throw off the whole system.

You shouldn't be venting your mains using the radiator vents.
Vent mains fast and radiators slow.

nicholas bonham-carter

No wonder you have had such problems with varying temperatures, with no main vents. Paying for extra fuel to force the air out of the tiny little vents on the radiator is certainly no fun for you or the tenants, who have to endure extremes of cold or hot.
Get the right number of main vents on the mains, and you will be on your way to having all the floors at similar temperatures.
When these systems were first installed, the occupants expected even temperatures, and the original installers provided that, along with silence, and economy. Now that your system has not been maintained properly, you must undo years of neglect and put those main vents in. They will probably pay for themselves in a couple of months.--NBC