Boiler w/ modine

Status
Not open for further replies.
Qojoe

Qojoe

Member
Location
Long island
Hey everyone, i was wondering if someone could lend me a hand. I dont really have much boiler experience or experience hooking up a modine. I have a small boiler (weil mclain part number 550-142-788/0712) with one zone, and a used modine (can be wired either 120/240 volt) with an aquastat and a fan timer switch on it. I was drawing up how i think it should be wired but i dont want to mess anything up. I will post pics of what i am thinking and pics of the actual items. Any help would be appreciated.
ee14a9d7539bad3cc77fc002bb860975.jpg

04e36f692d3f7c38cf27673866d7131e.jpg

ec55c3b98e3e68083c61a69a99d8140e.jpg

bbd524b9a95190bd2aeb2b501224910e.jpg


Sent from my SAMSUNG-SM-N920A using Tapatalk
 
Aquastat is normally part of the boiler and doesn't need field connected. It monitors boiler output temp and controls the burner. The room thermostat should control the zone valves and pumps, which with a single zone system I have at times seen set up so the pump runs continuously.

What you have appears to be controlling the fan - with that arrangement the room thermostat called for boiler (and maybe the pump) and when enough heat reaches the heat exchanger the fan starts via the temp switch you are questioning.

Sorry looked again and what you have on the heat exchanger is a timer, probably with 24 volt control circuit. It is likely initiated with 24 volts and has off delay function on output after losing 24 volt input. Still can't believe the aquastat isn't a part of the boiler though, you shouldn't need to touch it.

Why don't you give us details of the low volt control terminals that likely are on that boiler.
 
Last edited:
Not an electrical topic, but I don't think the galvanized pipe for the gas piping is compliant with gas codes either. LP gas - IDK, pretty sure NG reacts with the zinc in the galvanizing.
 
0419d84331efdcd5dd5441a69535f71d.jpg


This is ths only pic i have of the controls. Yeah they just want the fan to come on when the temp falls below a certain temp. So your saying i dont need an aquastat at all?

Sent from my SAMSUNG-SM-N920A using Tapatalk
 
The low voltage thermostat needs to open a zone valve or power circulator pump for the hot water zone to the Modine. The strap mounted aquastat breaks power to the fan so that it doesn't run until there is hot water flowing through it. Otherwise it blows 'cold' air. I've wired tons this way. If this is the only zone on that boiler then you would just have the low voltage t-stat wired to TT on the boiler control
 
Sweet so does mean i can get rid of the fan timer switch? Sorry its making a little more sense but still a little confusing. So if the aquastat is hooked to the fan how does the boiler know when to kick on.

Sent from my SAMSUNG-SM-N920A using Tapatalk
 
Just thinking bout it more in depth, if i connect it according to my diagram and run a low volt 2 wire from the fan timer to the boiler wont that be correct

Sent from my SAMSUNG-SM-N920A using Tapatalk
 
kwired said:
Not an electrical topic, but I don't think the galvanized pipe for the gas piping is compliant with gas codes either. LP gas - IDK, pretty sure NG reacts with the zinc in the galvanizing.
Click to expand...
I believe that varies geographically depending on the quality of the natural gas supply. In some areas, or in times past, the sulfur content of natural gas is/was high enough to react with the zinc. Where the sulfur content of the natural gas is low enough, I believe there's no problem using galvanized pipe or fittings.

Cheers, Wayne
 
Qojoe said:
Sweet so does mean i can get rid of the fan timer switch? Sorry its making a little more sense but still a little confusing. So if the aquastat is hooked to the fan how does the boiler know when to kick on.

Sent from my SAMSUNG-SM-N920A using Tapatalk
Click to expand...

Yes, get rid of the timer, it was from a previous life apparently. Simplest way to do this- fan gets wired through aquastat on it to 120V. Boiler gets wired to the thermostat on the wall. (This is a packaged boiler so just provide power to it and connect the LV 18/2 thermostat wire from the thermostat to the bk/wh zip cord sticking through the left side of the cabinet.

How it works: thermostat calls for heat>boiler starts along with circulator>when water is hot> aquastat on fan coil turns on fan. (Set aquastat to around 120 deg. set boiler to 160.)

And I also take issue with galvanized for NG.

-Hal
 
It might not be an issue but the fan will continue to run after the call for heat is satisfied until the temp at the aquastat cools down.
I usually put a small relay at the fan that lets the fan start with the aquastat but shuts off the fan when the thermostat is satisfied.

This insures that you are only blowing heated air out but if your only doing a garage or basement it may not matter.

Also you don't have BTU sizes for the boiler or the Modine posted, Those Modines can really suck the heat out of the water causing condensation/corrosion issues if the boiler can't maintain minimum temperature.
 
I usually put a small relay at the fan that lets the fan start with the aquastat but shuts off the fan when the thermostat is satisfied.
Click to expand...

Yes, I've done that too but I wanted to keep this as simple as possible. I've used a Honeywell R845A https://www.google.com/url?sa=t&rct...n2juSdvc3GrxKw&bvm=bv.142059868,d.eWE&cad=rja

It contains it's own transformer. 1&2 to power, TT to thermostat, 3&4 in series with aquastat and 5&6 18/2 to TT on boiler.

There are also other schemes to keep the water warm to prevent a freeze-up if you turn the heat off. (Boiler in house, fan coil in garage for instance.)

-Hal
 
GlennH said:
It might not be an issue but the fan will continue to run after the call for heat is satisfied until the temp at the aquastat cools down.
I usually put a small relay at the fan that lets the fan start with the aquastat but shuts off the fan when the thermostat is satisfied.

This insures that you are only blowing heated air out but if your only doing a garage or basement it may not matter.

Also you don't have BTU sizes for the boiler or the Modine posted, Those Modines can really suck the heat out of the water causing condensation/corrosion issues if the boiler can't maintain minimum temperature.
Click to expand...
Looks like circulation pump is controlled by the boiler - so if room thermostat ends call for heat circulation pump should stop - won't take very long for fan coil to cool off enough to shut down on low water temp if the circulator has stopped pumping.
 
kwired said:
Looks like circulation pump is controlled by the boiler - so if room thermostat ends call for heat circulation pump should stop - won't take very long for fan coil to cool off enough to shut down on low water temp if the circulator has stopped pumping.
Click to expand...

Looking at the pics, it looks like the aquastat is mounted on the supply at the top of the fan, this is where the hottest water is, taking the longest time to cool down. I usually put the aquastat on the return for this reason.

We also don't know how this is going to be piped, If it is going to be just this one zone a flow check may not be installed. This will allow water to circulate by gravity after the circulator is shut off prolonging the time the fan continues to run. Depending on what space this is heating it may or may not be a bad thing.
 
Status
Not open for further replies.
Top