Controlling an hydronic Modine garage heater with a thermostat

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Old 11-12-17, 10:53 AM
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Controlling an hydronic Modine garage heater with a thermostat

A bit perplexed by the Modine gas heater in the garage of the house I am renting. It is a great feature and would love to have it turn on at like 40 degrees in the garage and maybe turn off at 50 degrees during the winter months, but I cannot figure out how to regulate it.

It has an Aquastat L6006C water temperature thermostat - with a 65-200 range. But I see no external probe for air temperature? How is this supposed to work? If I turn the limit from 200 down to 120 it goes on; then turns off at like 100, but unclear to me how this translates into air temperature range?
 
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Old 11-12-17, 11:02 AM
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Welcome to the forums.

You need to understand and identify what you have first.

You have a hydronic heater there. It doesn't use gas..... it uses hot water from a boiler to heat a coil. The aquastat turns the blower on when the coil reaches the set temperature to keep from blowing cold air around.

You can add a 120v line thermostat in the blower line. However, based on how it's connected to the heating system.... when the boiler runs.... the coil gets hot... whether or not the blower is activated.

That may have been installed by the owner to keep a certain area hot enough to prevent a freeze up. Keep that in mind when changing the adjusted temperature.

Remember.... a renter has no right to do electrical work. If you intend to do any wiring work you must have the owners permission.
 
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Old 11-12-17, 11:36 AM
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Yes - right, should not have said gas. It's driven off the furnace with hot water. Okay so the aquastat controls is wired to a coil that turns the blower on/off - but what is calling for the demand for the boiler to send hot water to the heater? If this is just a zone - I would have a Thermostat talking back to the furnace. But there is no thermostat?

The landlord understands that the heater should work as I describe - so are in agreement that it needs to be fixed.
 
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Old 11-12-17, 11:59 AM
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Ok.... this thread is now in the hot water forums and the title reflects the unit.

There should be some way to control the flow of hot water to the unit.

Does the main heating system use zone valves or circulator pumps ?
Can you get to the boiler and the controls ?
Can you trace the water lines from the garage heater ?
 
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Old 11-13-17, 08:13 AM
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Thanks Pete.

The house has zone valves. It is hard to trace the piping back. The heater hot water pipe goes up into the ceiling of the garage. I can only guess where it comes into basement - very old basement, original house built in 1800; renovation with garage built 20 years ago or so. Best I can tell it - with much uncertainty linked to Zone 2; which I believe is the "great room" located above the 3 car garage.

It seems that the hot water loop may just come off of the baseboard heating of the great room above. If that is the case, I'm guessing the demand for the heater may come from the great room above thermostat. So sort of an indirect system - If room above calls for heat - and hot water gets sent to great room; also diverted to heater in garage. Aquastat in garage heats up "on pipe aquastat copper probe" - when temp hits "set point" say 160 degrees - the heater/blower kicks on. Does that sound right?

If the heater is not on own zone - seems I will not be able to do what I want to do. As IF heater is not on own zone, it can't have own thermostat? (Or it could but then would heat up great room above - when garage was cold).

So seems, I have a few options to work out with landlord, if I don't want this heater blowing air randomly based on the great room thermostat:

1. Set the "set point" higher than the furnace water temp of 170 degrees. If I set the aquastat at 170 or above - the pipe can never get that hot and turn on the heater.
2. Disconnect the heater wiring.
3. Live with it - the way it is; accepting "indirect heating" of the garage based on great room thermostat.

Does that sound right - are there other options?

Sounds like
 
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Old 11-13-17, 08:29 AM
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Thermostats can be added to any modine unit AFAIK...

Here is the choice from modine..

Honeywell T4051A1003, 50-80F range, 16A @ 115V, 8A @ 230V
Honeywell T451A3005, 44-86F range, 9.8A @ 115V, 4.9A @ 230V
Johnson Controls T22BBC-1, 40-90F range, Auto/Off/Fan switch, 10A @ 115V, 4.9A @ 230V

As stated talk to the landlord....
 
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Old 11-13-17, 09:25 PM
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You can add a thermostat in series with what's there. That would allow you to keep the heater from coming on until the temperature you set is met. The coil would heat up whenever the zone was active but the fan wouldn't blow.

If the zone that supplies that unit is not on.... there is no way to get heat from that heater.
 
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Old 11-13-17, 10:00 PM
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It would need to be piped as a mono flow tee system on the modine and great room and have thier own zone valves there to have better heat control.
 
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