NEW IN-FLOOR SETUP IN THE SHOP

[DaBackBurner]

To answer everyones questions, my tarm is "Solo 60". So far above 25 degrees equals one fire per 24 hrs. Lower than 25 degrees equals one fire every 12 hrs. I have figured out to not let the bottom of storage get below 120 due to termovar function upon restart. Jebatty, I liked the option you described, because I don't always want my shop at 60 degrees. If I leave for a week or go on vacation I would probably turn it down and let the unit heater due a quick recovery when I'm home. I understand thermal mass but I want to keep it easy for my wife and kids to do the boiler. I want to use gylcol for the shop loop. I already have about 40 gallons from a friend. The heat exchanger I have in my basement has 1- 1/4 supply and return from boiler, but the problem is it has a 3/4 inch restriction where it ties into the 1 -1/4 inch thermopex. It is a stainless tube in shell pool exchanger.

DBB: I don't understand outdoor reset or injection mixing circuit. If you could explain to me what type of mixing valve has a CV close to total flow? I don't understand what all that means? I have a WATTS 3/4 inch mixing valve, but don't know if that is correct. Also, if I go one pump, will I burn more electricity with the high head pump vs. two small pumps?

Thanks for all the imput. Jim

Cv = Flow coefficient or flow capacity rating of the valve and it is typically chosen close to the total flow of the distribution loop for a 1psi drop which equates to 2.3ft of head that the pump must overcome. So for example if you needed 5gpm flow and had a lower Cv valve say 3, your pump would have to overcome more pressure (psi) or head to flow those same gpm's. Most manufactures list their valves Cv or can be looked up at least, and it is fairly common practice to match a valve's Cv to the total flow which also allows the valve to mix properly.
I don't actually know your heat loss so I can't give you any suggestions but my guess is that your valve may be just fine, there is after all some 'lee-way'. It's also hard to determine whether or not one pump vs. two will save you electricity without knowing your heat loss.
You most likely would save electricity by going with, as ew pointed out, a variable speed ECM but probably only involving injection mixing (a whole other animal) because the pump would vary its speed and typically only run at 30-50% rated output hence electricity savings.
Once your heat loss is known many things can be determined...or at least calculated.

Oh yeah.... GO PACK (forgot that last time, hehe)

 

[kuribo]

Thanks for the info...was looking at injection pump systems....much easier to just vary supply temps...

My tubing is already placed (1/2", about 6" oc). At max output of 35 btu/hr./sq ft, using the standard of .6 gpm from above, I get a supply temp of 125F, a delta t of 14.5F, and a total flow of about 5 gpm on the first floor which is tiled, and a supply temp of 107F in the basement which is bare concrete, a delta t of 14F, and a total flow of 10 gpm. All told, about 100,000 btu/hr. Calculated heat loss on the design day is about 85,000 btu/hr so I have a little extra capacity....Is this roughly what others are seeing?

Now to figure out what type of supply/distribution system to use....

 

[jimdeq]

Sorry for not getting back to this topic for awhile. We had some health issues in the family. I want to move forward with the infloor. Today I ordered materials to get started. I still havent decided on the one vs two pumps. I leaning towards two pumps for the simple reason that I dont want to get it done and find out I do not have a big enough pump or my electric bill goes up $25.00 a month.

DBB, I appreciate all the math you did for me and it was a big help. I had a contractor do a heat loss and he came up with 20,000 BTU. I have a very similiar building to Jebatty. I want to keep things simple and it seems one pump would be much simpler. Glycol is the other issue as to how it will impact my heat calc. The variable speed Alpha 15-55 ECM would be awesome if it could handle the 300' transit and the 6 loops. Then the unit heater? I would think the 1-1/4" thermopex would keep the head down ,but it is still a long transit.
Any more comments would be appreciated.

 

[ewdudley]

Sorry for not getting back to this topic for awhile. We had some health issues in the family. I want to move forward with the infloor. Today I ordered materials to get started. I still havent decided on the one vs two pumps. I leaning towards two pumps for the simple reason that I dont want to get it done and find out I do not have a big enough pump or my electric bill goes up $25.00 a month.

DBB, I appreciate all the math you did for me and it was a big help. I had a contractor do a heat loss and he came up with 20,000 BTU. I have a very similiar building to Jebatty. I want to keep things simple and it seems one pump would be much simpler. Glycol is the other issue as to how it will impact my heat calc. The variable speed Alpha 15-55 ECM would be awesome if it could handle the 300' transit and the 6 loops. Then the unit heater? I would think the 1-1/4" thermopex would keep the head down ,but it is still a long transit.
Any more comments would be appreciated.

I think DBB's number for the flow rate from house to shop might be off. He's showing 5gpm, but if heat flow is 20000 btu / hour, and deltaT is conservatively 50 degF, the flow from house to shop would be no more than 1 gpm. Therefore house to shop headloss would be more like a foot or less.

Bottom line, one small pump, e.g. 15-58 or 008 should have no problem pulling all the way from the house and through a mixing valve. Keep in mind that the flow from house to shop will be only enough mix the radiant supply up to 120 degF or whatever, and that the return temperature to the house would be that of the return from slab, quite low.

The high temp heater, if implemented, would have its own pump drawing in parallel with the radiant pump.

--ewd

 

[woodsmaster]

I'm not an expert, and in my opinion all those fancy controls are really not nessasary. Sure It's fun to play around with the stuff
but for a shop? I have a single 3 speed circulator and a mixing valve. Works great.
As far as freezing I've left my circulater off in the shop for 4 days and only droped 10
degrees and thats with cold vehicles going in every day. My power would have to be out for weeks to have somthing freeze.
By the overhead doors I left the pex back a couple of feet from the edge so as to not waste heat to the outside and for no worries about freezing. Have fun with the install.
My 2 cents.

 

[jebatty]

I’m not an expert, and in my opinion all those fancy controls are really not nessasary. Sure It’s fun to play around with the stuff, but for a shop? I have a single 3 speed circulator and a mixing valve. Works great. As far as freezing ... power would have to be out for [a long time] to have something freeze.

I pretty much agree, even though I am one for fancy controls, monitoring, data logging, etc. My shop has a single speed circulator, mixing valve, set it and forget it on the floor sensor, no reset. A few degrees variation in air temp in the shop just doesn't make any difference for anything I do. As for freezing, I do have antifreeze in the floor pex, use a plate hx, but boiler and storage tank in the shop are water. I have been gone for 2 weeks in some very cold winter (-10 to -35F), no freezing. My backup simply is a 5000W - 240V space heater to keep the air temp about 50F during long absences. I figure that will heat the floor as well as everything else to prevent freezing. Much less expensive than any alternatives, and rarely used. All pex is 12" o.c., except for first three passes around the perimeter.

 

[DaBackBurner]

I think DBB's number for the flow rate from house to shop might be off. He's showing 5gpm, but if heat flow is 20000 btu / hour, and deltaT is conservatively 50 degF, the flow from house to shop would be no more than 1 gpm. Therefore house to shop headloss would be more like a foot or less. --ewd

:lol: That certainly wouldn't surprise me.

My limited experience with my shop floor (slab on grade with 2" xps perimeter and below slab) is that last year I ran a ΔT of 40-50 for the shop loops. This didn't fair too well for me because I needed a fairly high supply temperature (120-130) because of my lower flow rates in those loops in order to maintain my desired air temperature. Because my loops are 6" OC at the perimeter and 12" OC for the field, with flow around the perimeter of the building first (this made sense as that should be the area of the highest heat loss) I found I was melting snow around the exterior of the building (after-all it is only R-10 we are talking about). This year I increased my flow rates in my loops to maintain a lower ΔT, now 10-20, and find that my supply temperature (80-90) into those loops can be much lower while maintaining my desired air temperature. As a result I have no snow melting around the perimeter of the building this year, which is always a good thing in my eyes because my distribution losses have been minimized. As on old-timer fluid mechanic for iron tailings told me "Flow too low is a big no-no, flow to fast and it just won't last, flow just right lets crack a Miller Light".

I'm really poor at this as well...but let's see some pictures.
Best of luck.

 

[ewdudley]

I think DBB's number for the flow rate from house to shop might be off. He's showing 5gpm, but if heat flow is 20000 btu / hour, and deltaT is conservatively 50 degF, the flow from house to shop would be no more than 1 gpm. Therefore house to shop headloss would be more like a foot or less. --ewd

:lol: That certainly wouldn't surprise me.

My limited experience with my shop floor (slab on grade with 2" xps perimeter and below slab) is that last year I ran a ΔT of 40-50 for the shop loops.

Not your in-slab numbers, I was talking about unmixed flow from the house to shop mixer, which I think you said would be 5 gpm, whereas I believe it would be less than 1 gpm, your in-slab numbers made good sense. The amount of unmixed flow to support the 20000 btu per hour heat demand should be tiny.

--ewd

 

[DaBackBurner]

Not your in-slab numbers, I was talking about unmixed flow from the house to shop mixer, which I think you said would be 5 gpm, whereas I believe it would be less than 1 gpm, your in-slab numbers made good sense. The amount of unmixed flow to support the 20000 btu per hour heat demand should be tiny.

--ewd

I totally agree Eliot, the numbers were incorrect for the loop from-to house portion. I didn't know, last year, that my supply manifold adjustable flow rate indicators were not fully open from the factory. I was under the impression that they would have shipped them that way. Silly me. This year I found out differently, what a difference.

 

[DaBackBurner]

I was just splitting some wood this unusually warm morning (crazy winter - no complaints) and went to check on the heat in the workshop and at this point I'm just gum flappin'...
Could he have put a mixing valve and pump in the house? Assuming his existing fossil boiler in the house was adequate to provide the extra BTU's (they are usually oversized anyway), couldn't one use that as the backup source? I'm proposing to do something similar this spring, albeit the other way around. It might be nice to control the heat in the garage from the house as well, not to mention easier to check if all your pumps are working from one location. Like I said, just gum flappin'.

 

[jimdeq]

Sorry for the delay fellas ,but I have been away from home for work. Here is a picture of my proposed plumbing diagram using the two pump system. Take a look at it and if anyone could provide imput or suggestions I would appreciate it. I am very intriged by the single pump concept , but dont understand how to pipe it. I have a Grundfos Alpha 15-55 and a 15-58 sitting on the shelf. The second picture is the 1 1/4" thermol pex in the basement of the house.

 

[DaBackBurner]

Here's one possible design that may work for the one-pump scenario.

 

[nate379]

Mine is same way and it sucks in the fact that the snow melt drains toward the door and then freezes the door closed. Only is a issue when it's cold out -20* though. I guess prying the door up is better than freezing the pex in the floor though.

By the overhead doors I left the pex back a couple of feet from the edge so as to not waste heat to the outside and for no worries about freezing. Have fun with the install.
My 2 cents.

 

[woodsmaster]

Mine is same way and it sucks in the fact that the snow melt drains toward the door and then freezes the door closed. Only is a issue when it's cold out -20* though. I guess prying the door up is better than freezing the pex in the floor though.

By the overhead doors I left the pex back a couple of feet from the edge so as to not waste heat to the outside and for no worries about freezing. Have fun with the install.
My 2 cents.

It rarely gets that cold here, and my floor slopes away from the door both inside and out.

 

[jimdeq]

Thanks DBB for the drawing. Seems like a simple plan and easy to pipe. I am going to show it to my buddy who is helping me with the plumbing. I also like the idea of controling the shop from the house, I hope the blue Cat5 wire you see in the picture will work for controls. Can you explain the diverter valve, I could not enlarge the picture to read all your comments?

 

[DaBackBurner]

Sorry about the picture.
Here is a link to one example of a motorized 3-wire control 3-way ball valve.
http://www.caleffi.us/en_US/Technical_brochures/01131/01131.pdf
When your garage is calling for heat and another mechanism (possibly an aquastat) determines the house supply is not hot enough, it puts the diverter valve in a bypass position, which closes flow off from the house supply, fires the backup heater and flow would progress through it instead. The common 'AB' side would be toward the mixing valve. The 'A' side towards the house and 'B' towards the backup heater (or vice versa).

 

[nate379]

Not allowed to have a floor drain here cause on septic so it has to slope toward the door for drainage. I guess could be flat but then it would pool somewhere, cause it's never "flat". I have about 1.5" slope over the length of the garage, 26'.. just enough.

Mine is same way and it sucks in the fact that the snow melt drains toward the door and then freezes the door closed. Only is a issue when it's cold out -20* though. I guess prying the door up is better than freezing the pex in the floor though.

By the overhead doors I left the pex back a couple of feet from the edge so as to not waste heat to the outside and for no worries about freezing. Have fun with the install.
My 2 cents.

It rarely gets that cold here, and my floor slopes away from the door both inside and out.

 

[DaBackBurner]

Sorry about the picture.
Here is a link to one example of a motorized 3-wire control 3-way ball valve.
http://www.caleffi.us/en_US/Technical_brochures/01131/01131.pdf
When your garage is calling for heat and another mechanism (possibly an aquastat) determines the house supply is not hot enough, it puts the diverter valve in a bypass position, which closes flow off from the house supply, fires the backup heater and flow would progress through it instead. The common 'AB' side would be toward the mixing valve. The 'A' side towards the house and 'B' towards the backup heater (or vice versa).

You could probably do this 'bypass' loop with two zone valves as well (might be cheaper). One N/O ZV (for the house supply) and one N/C ZV for the backup heater. When the aquastat reaches it's set point it opens the backup heater N/C ZV and when this is fully open triggers the house supply N/O ZV to close. I'm not a controls guy and defer to the other more experienced posters on this forum, but this seems like it may work.

 

[jimdeq]

OK but I dont want the unit heater to be set on anything that automatically turns it on other than me or the thermostat. I want to keep the shop warm ,but not hot. I understand the benefits of not letting a large thermal mass cool off. I dont know what temp I will keep it at ,but probably around 50. The only time I will use the high temp unit heater is when I am home and probably have a fire burning. Thats why I want the unit heater on its own stat and controls. I dont want the unit heater running if know one is home or working in the shop. I was thinking that when I added the unit heater that would have it's own circ that would kick on in tandem with the primary circ ,but not sure about that either. I really like the one circ drawing DDB made if that will work for my situation. I got confused when you added the three way motorized. Would the same drawing work without using the diverting valve or does the diverting valve save me from sending hot water back to the house that could go back to the infloor zone.

 

[DaBackBurner]

OK but I dont want the unit heater to be set on anything that automatically turns it on other than me or the thermostat. I want to keep the shop warm ,but not hot. I understand the benefits of not letting a large thermal mass cool off. I dont know what temp I will keep it at ,but probably around 50. The only time I will use the high temp unit heater is when I am home and probably have a fire burning. Thats why I want the unit heater on its own stat and controls.

Sorry about the confusion Jim...then I would suggest using the unit heater as a stand alone circuit possibly connected to a modine or something similar that is a low mass heat emitter then, so you can quickly raise the temperature in your garage at your leisure. Use the slab radiant as a base temp from house supply only. The additional heater would not even be part of that circuit then.

 

[jimdeq]

Exactly DBB. So if that is the case would you suggest another pipeing diagram. I know it is alot of work ,but I would appreciate it. I cant find any diagrams similiar to what I need?

 

[DaBackBurner]

Just remove the 'backup' heater out of my previous drawing along with the diverter valve. Install a slab sensor for your radiant loops that controls the pump, and maintain whatever slab temp you would like, with the mixing valve, as a base air temperature.
The low mass heater is a stand alone unit that has no bearing on the piping diagram anymore. A fossil Modine unit could be used or similar. Something that has a quick enough response to bring your base air temperature up to your desired air temperature while you're out there. That unit would have it's own air temperature T-Stat.

 

[ewdudley]

diagrams similiar to what I need?

This might do it.

 

[jebatty]

FWIW, this is my setup, which I regard as very simple. Shop is similar size to jimdeq's; similar climate; 6 loops of 1/2" pex @ 275' +/-, 6" o.c. near perimeter and then 12" o.c.; supplied from a 5" x 12" x 30 plate hx with a Taco 009 to the floor loops. Building has 2" foam perimeter insulation down 3', and 2" foam under entire slab. Sensor embedded in the slab about 4' in from perimeter controlled by a Ranco, constant setting 61F, 1F differential. Also a stub out for a unit heater which I have not installed and have not needed. Shop air temperature may hit a low of about 50F at -35F outside temp, typical air temperature 56-63F during winter depending on outside temp. 50% antifreeze in floor loops. 100F+/- supply temp to floor via mixing valve; loop flow based on flow meters on manifold is 2.75 gpm, typical delta-T=30F+/-, typical floor btuH = 40,000+/- when radiant circ is "on"; typical building heat loss 12-14000 btuH, max is about 17,000 btuH. Building has one 12' x 12' residential style, insulated OH door, 1 - 3' steel insulated entrance door on front; 1 - 4' wood access door on rear; 2 - 2' x 4' insulated windows on sunny side of the building. Building dimensions 32' x 48' x 14'. 6" fiberglass in walls R-19; R-39 minimum blown-in fiberglass in the ceiling.

Comments/differences from jimdeq: The unit heater may need to be plumbed between the HX supply/return lines rather than shown, which is more like supply from a primary loop. I plumbed this way because I felt that if I needed the unit heater, the radiant floor circ likely also would be "on", and I also can manually turn "on" the radiant floor circ so that I have the function of a primary loop. But as mentioned, I have not needed to install the unit heater. My Tarm Solo 40 and 1000 gal pressurized storage is in the building; Tarm serves only the building, no other heat load. Tarm functions to load storage. Radiant is supplied separately from storage as required.

The diagram does not include the air separator and expansion tank for the radiant, isolation valves, etc.

I stubbed out for the unit heater before the mixing valve so, if needed, it would be supplied with the hottest water, and then return to the hot water line for use by radiant, which only needs 100F water via the mixing valve. I guestimate unit heater delta-T not greater than 20F and probably less. I also have a 5000w-240v space heater to provide supplemental heat if I am gone for a period when I might be concerned with freezing, as the Tarm and storage are water, only the floor is glycol. Supplemental heat may not be needed if the HX/shop was all glycol and freezing was not a concern.

 

[DaBackBurner]

I should add that I was referring to a non-hydronic low mass modine unit, vented out the side of the wall for instance, since I neglected to even ask what type of unit heater you had.