Tagaki JR thermostat control

[Throttlejockey]

Okay so I went away from the LP water heater and installed a Tagaki JR. How are you guys controlling the temp?

Do you control it by a thermostat wired so the pump shuts off at the set temp? Seems like it will run forever that way since it takes so long to get the slab up to temp.

 

[stingry]

Don't have my system up and running so can only relay what I have read. The pump will run until the slab is up to temperature then shut off. Then, when the thermostat calls for more heat, the pump will come on, the Takagi will sense flow and begin to heat water. Then when the thermostat is satisfied, the pump will shut down, as will the Takagi.

Cheers
Steve

 

[DuramaxPowered]

Exactly, the Takagi will turn on only when water flows. I am hoping to have my in floor heat hooked up by next weekend. I have a 36x54 pole barn with 7 loops of 1/2" PEX, 290' loops. I'm using a Takagi TK JR, single Taco pump, 1 Zone taco zone controller, and a thermostat with slab sensor. Most of the parts arrived here Monday, but the last few things won't be here until tomorrow.

 

[Throttlejockey]

I think I need the slab sensor. Seems to me once the slab gets cold you're starting all over.

 

[tdkkart]

I think I need the slab sensor. Seems to me once the slab gets cold you're starting all over.

The slab never gets "cold", it will always be a few degrees warmer than the ambient room temp, this is how it heats the room. The heat loss of the room will determine how much warmer than ambient the floor needs to be in order to maintain the air temp. IE: if the heat loss of your room is 10BTU/sqft/hour the floor temp will have to be 65* in order to maintain 60* air temp. At 20 BTUH the floor temp goes up to 70* for the same 60* air temp. The floor in my pole building is typically 3-7* higher than the air temp depending on how cold it is outside.
When a standard wall thermostat calls for heat the system adds heat to the floor till the room temp comes back to desired. The system only boosts the temp back up a couple degrees.

The only time you should need a slab temp thermostat would be if your room has some heat source other than the floor. IE if your room has large south facing windows that raise the room temp enough to satisfy the thermostat for several hours. In this case the floor may lose more heat than normal and require more input to "catch up" after the other heat source goes away.

 

[scuba0459]

TDKKART

What a great explanation. Thank you

Albert

 

[Throttlejockey]

Thanks for the replies. It seems to be working great now.

Boy, that heatinghelp.com site condemns on demand heaters.

 

[scuba0459]

I have demand hot water in my house. We love it. I did not do it in the shop because the systems I am aware of require you to reset it if the power goes off. I would hate to be away and have the system shut down and then freeze. Keep in mind that it can get real cold here. Last winter we hit -47c (-52f).

I would have liked to have a high efficiency water heater but I doubt that I would see a payoff over the life of the water heater.

I did do a heat loss calculation and my heater is twice the size the calculation suggested. The gas line to the garage is also oversized and can provide 175,000 btu if required.

Albert

 

[99_xc600]

I use a Takagi TkJr in my house for domestic hot water and absolutely love it. Have had it for 5 years and have had only one issue with it.

The unit is somewhat sensitive to dust intake into the heat exchanger. My unit is installed within my laundry room and uses the house air for combustion. So what happens, even with the pre-filter. It will take in some of the dust and dryer lint into the intake and I will get a flow issue. (The heater will cycle on and then shut off because it can't get enough airflow through the heat exchanger).

I spoke to Takagi and they sent me the instruction's on how to remove the heat exchanger and clean it. A very simple process and takes about 20 min now that I've done it a couple of times.

I do the cleaning once a year to keep it running at it's best. So really it's not that big of a deal.

I figured I would pass this along, not sure if you have a dusty or dirty enviroment. Just something to be aware of.

Also as far as setting the water temp, there is a set of rocker switches inside the cabinet. Factory is 118*, but using the rockers you can raise it to like 165* ( I think..It's listed in the user's manual) Anything higher than that, you can purchase an external remote to set it.

 

[Throttlejockey]

Thanks for the tips. I tried the 112* setting and the 122* setting seems to work great now.

I already had a 3" PVC pipe in the wall from the Bradford White water heater I had before.
So, what I'm going to is install the adapters to make it a closed combustion chamber using the existing pvc, so that worked out well. Fumes still scare me.

 

[DuramaxPowered]

I fired my floor heat up last night at 6PM, slab temp was 22*F. I don't have the ceiling metal/insulation installed yet. The walls are done, but ceiling won't be done until next weekend probably. I just went out and checked it again at 8am it was at 32*F. I expect it to be around 40*F at 6PM tonight. I'm just trying to raise the slab temp up to 40 or so, to take some of the cold out to finish the ceiling up. After that I'm going to set it at 60* for the rest of the winter......This is a 36x54 with 15.5' walls!!!!!!

 

[DuramaxPowered]

I don't have the slab sensor mounted in the slab yet, just sitting on top and air temps were lowering the reading. I an 8"x8" piece of 2" Foamular 250 over the sensor to block air from reaching it for now. The slab temp is 51*, without the insulation I was getting a 36* reading.

 

[DuramaxPowered]

I'm proud of the final product, considering it was my first time sweating copper pipes.

 

[tdkkart]

I'm proud of the final product, considering it was my first time sweating copper pipes.

Looks good. Looks like you've go the same manifolds as I do.

If your slab is at 50* I'd back off for awhile. 50* slab will give you 45ish if your're insulation was done, 40+ probably as it is now. I'd back it down for now, you'll be burning a tone of fuel for no reason otherwise.

 

[DuramaxPowered]

I have about 25% of the ceiling metal installed. We're going to put more up this afternoon/evening and during the week. I'm hoping to be done and blowing the insulation Thursday. For now, it's really nice to have a floor that is above freezing!!!!!

 

[Throttlejockey]

I'm proud of the final product, considering it was my first time sweating copper pipes.

Looks good. You may need 3/4" pipe all the way to the unit though. Heating that many loops you may not get enough supply if it calls for high BTU's.

 

[DuramaxPowered]

All the copper from manifolds to heater is 1".

 

[Throttlejockey]

All the copper from manifolds to heater is 1".

Sorry should have been more clear. I meant the propane supply.

 

[DuramaxPowered]

Gas line seems to be flowing enough volume. It is a 7/8" ID natural gas line but it is about 190' from the meter. I raised the slab temp from 22*f to 55*f in 22 hours

 

[stinkity stoink]

Duramax. Where did you pick up youre supplys locally or internet. I am planning on using the takigi for my set up.
What is the box that is on the wall with the electric? Is that the slab sensor. I am still not sure exactly how to set mine up. I am 24x26 with 3 loops. I don't have a slab sensor just a wall thermostat.

 

[DuramaxPowered]

www.pexsupply.com for most of the parts. The box on the wall is a Taco 1 zone relay. The thermostat calls for heat, zone relay closes, and the circulator pump kicks in which causes the Takagi to fire up.

 

[stinkity stoink]

Thanks. Duramax. I hope to get mine up.