Radiant Floor Heating System 404x40 shop

CarGuy

Temp setting for water heater

The temp setting for the water heater is 102 now.  I was at 100 and that worked well, I was just experimenting a bit.



I may be a little off on my 10-20 minute run time estimate.  I have been working out there organizing and not really paid attention to the time the system is pumping but I will tomorrow.



Thanks on the system.  I cannot take all the credit.  I did the pex layout, pex install, the manifold install and plumbing and a few other things myself (with some advice from one of the Pros on this site), then I called in a local Pro to plumb the remainder of it.



Here is a photo of my Pex install... would you believe that there are NO pex uncoilers available for rent (or for sale) within 1/2 hour of where I live... and some rental places had never even heard of it!!  So I improvised and used the Pex carton with a few other handy items around the garage, modifying it into and crude "uncoiler" .  I did it myself to save any family or friends that wanted to help the brunt of an occassional bout of frustration!



Chris

furnacefigher15

Looks like a clean install

The install looks clean, but a couple things.



#1 - I don't see a relief valve in the photo (may be angle of pic). If there is not one, get one in pronto.



#2 - The heater will cycle no matter what you do b/c its output capacity is more than the load and flow you are giving it, and I would leave it that way, unless once its colder, you don't get the heat you want. As long as the off cycle is lengthy.



3/4 inch pipe is good for 40,000 btu at 4 gpm and you are moving fairly close to that at 3.4 you will move 34000 btu



The tankless is likely a 3 stage burner (also has internal bypass to temper to setting) with a peak output near 100,000 btu and lowest setting just a hair above 40,000 btu



If you find you need more heat, you will need more flow (bigger pump, or a 2nd in series), but there is a good chance everything will be fine as is.



Good luck

CarGuy

Pressure relief valve?

Thanks Furnacefighter15.  Do you mean a pressure relief valve? There is a system air vent/bleed on the manifold.



Chris

CMadatMe

Relief Valve

I also don't see one. Need to install one and make sure its a 30lb boiler relief.. Your delta-t, which should be 10 degrees for radiant slab is only going to allow you 15,000 btus delivery.



3gpm x 10 x 500 = 15,000 btus



Why did you pick this unit that can only make 6.6gpm when your design called for more then 8gpm? I also noticed the design shows 40% gylcol mix thus why the high head of 14' in the radiant. The Takagi manual clearly states that the pump must not deliver no more then 4gpm through the tankless. At 4gpm head is 20'. At 3 gpm head looks to be on their chart 12'.



Your getting pretty much all the unit can do.

furnacefigher15

Yes pressure relief valve

The air vents are fine. The pressure relief valve is to allow the water an escape in case something goes wrong with the compression tank, or burner, or a fire etc....



If you don't have one sized at 30 pounds blow pressure and at least 510,000 btu capacity, shut off the boiler NOW, because you have a possible bomb on your hands!!!

CarGuy

Will get the pressure relief valve

I will get the prressure relief valve in place, thanks!  Chris, are you reffering to the 26-99 pump max'ing at 6.6 gpm?  I didn't have a deifinate design, I honestly did not realize/understand that I would need 8 gpm fo this (to get a specific outcome)... the examples Ironman posted were for my layout of the pex at the time. 



I already had all the components and wanted to try to make them work if possible.  I followed Rob's advice and used it all except the mixing valve and it seems to be working exactly as he predicted it would.  Comments on the Taco 007 not doing the job jive with everyone, so I chose to up the pump to the 26-99. 



Some more info on performance... I was in the shop today for 4 hours with the room temp thermostat set at 55 F.  Outside right around freezing all day.  When I got there the room temp was 55.7 degrees and the system did not come on once during that time.



Chris   

CMadatMe

Brads Post

I based it on Brads post. I did also look up the unit. The manual specifically states unit can only make 6.6gpm. It slso goes on to say pump should be sized to move no more then 4gpm through the hx. At 4gpm the head in the tankless is 20'. Your getting all you can out of the 26-99 and just about all the tankless can give you. As long as you happy with the temps your good to go.

CarGuy

Very happy...

Thanks for the extra info/details Chris.  Yes I am very happy with the temps and the performance. 



Also, I just checked, and the Isolation Valve Kit that I bought to go with the Takagi have the pressure relief valves built in.



Chris

NRT_Rob

10 deg dt??

this is a shop. you can push 30 degree dt easily. the heater is built for 60+ degree DT.

woodworker88

To much temp drop

I also had a company that sold me a system but was no help when it didnt work right.  Here is a little background on the system and layout.  I have 2 inch foam on the perimeter and the floor, I ran 7/8 pex cause thats what they told me to use(bad idea), I have 3 - 400 foot loops on a 24 by 40 floor.   I know you are supposed to to not run water more than 120 in a concrete floor but I turned it up to 140 cause I was only getting 80 degrees on my return with 1.6 gpm so I did some modifications to the piping and now am getting 90 on the return.  Oh yeah forgot to mention I have a 15-58 pump and a Tagaki Jr once again cause that is what they told me to get.  I would like to drop my outgoing temp to 120 and have a temp drop of 15 or so, Do you think I need a bigger pump or i seen someone talking about a pump for the heater and one for the tubes, how is that done?

NRT_Rob

I don't deny

that your setup is suboptimal. but why do you care if you have a 15 deg dt? in a shop, even 30 is fine.



140 is the max temp for concrete.

woodworker88

response

I guess I don't care what my drop is but with 140 degree water going out and all I get coming back in is 85 or 90, I just want my return water to be higher so it helps heat the floor better.  And this is my house not shop

NRT_Rob

ah, gotcha.

you are probably going to want to go primary/secondary then.

woodworker88

primary secondary help

Any help with how that gets piped in to the system

Tim Potter

Invaluable Books

I sure got a bunch of help from this site when redesigning my system, but I also think

Dan's books are worth their weight in gold

Click "SHOP" in the title bar,



http://www.heatinghelp.com/products/Hot-Water-Heating-Books/26/99/Primary-Secondary-Pumping-Made-Easy



http://www.heatinghelp.com/products/Hot-Water-Heating-Books/26/100/Pumping-Away-and-other-really-cool-piping-options-for-hydronic-systems



It sure helps to understand how to set up correctly, and why the forces work like they do