Hi everybody! Fist post, looking forward to some learnings. I just finished a 3 year basement refinish and we're enjoying it's additional space and features (120" projection TV is my favorite). So my problem. It's chilly in the basement. Our house was a spec home, came with Geo Thermal heat, which works great but with only 4 heat vents in the basement it's a cool 62. This is much better than the pre-insulated days when it was 55. Builder installed some type of radiant floor system but other than the 8 tubes sticking out of the floor I have absolutely no other information on what was done or what the plan was. I need something to supplement, or even become the prime heat source for the basement. I know first step is load calculations/heat loss. Based on unknowns how do I approach?

What do you have for a water heater?

8 exposed tubes would imply 4 circuits. You can determine the circuit length by determining the circuit volume by filling with a known volume of water and applying some basic math. What is the heated floor area? If you know the circuit lengths and the heated floor area, you can determine the tube spacing. Once you know the circuit lengths, spacing, and the heat load requirement, the HR design can be easily accomplished.

Or you can read the tube length normally printed on each foot of PEX tubing...

what is the square footage of the room?

Spec home with geo....

Probably an electric hot water heater w/ desuperheater.

OP hasn't been back, maybe just wanted to brag about the 120" TV, LOL

Chris

I hope OP returns because I really want hear how he determined the lengths of his circuits that are embedded in concrete by reading what is printed on each foot of PEX tubing... Yes Chris, why is it always about size...LOL!

Even those without real field experience can figure that one out.

Really Badger, why don't you tell us? I thought you had hydronic radiant field experience? Don't you at least have hydronic radiant in your home?

Posted By BadgerBoilerMN on 08 Jan 2015 11:59 AM
Or you can read the tube length normally printed on each foot of PEX tubing...

Thumbs Up......hahahahaha

Is it that critical to know the tube length?

Hydronic heating in my Homes, yes since 1990 thank you.

I do have field experience. Eat your heart out. I will type more slowly this time so it doesn't go over you head.

I would approach the the manifold carefully, lean over, pulling my glasses up for a closer look at the foot markings printed on every foot of nearly every PEX tubing available today.

Now here is the tricky part: You must record the tubing length of the supply and the return subtracting the lower from the higher numbers and voila', you have the loop length.

There is simply no substitute for experience, or your smarmy attitude for that matter. And you wonder why the OP has run off?

Arcamm, the circuit length is needed to select the correct pump to provide the required circuit flow rate at the required circuit supply temp to generate the required heat gain for the zone that the circuits provide. More circuit length translates to more pipe hydraulic friction and more required pump head for the same required circuit flow rate. You should also keep the length of all circuits on the same manifold within about 5-10% of each other. Fluid flow rate, like electrical current, takes the path of least resistance. So, to avoid disproportional heat flow to different sections of the floor, you should strive for equal circuit lengths that are on the same manifold.

Badger, you are the funniest person I know, LOL! I know you are joking (or perhaps are just a joke), but just in case anyone reading this doesn’t get it, the OP only had a few feet of PEX sticking out of the concrete slab with nothing recorded. The correct phrase is that there is no substitute for GOOD knowledge and experience. Unfortunately, that isn’t something that you have as is well blogged by your customers who have experienced your experience. Sorry I didn’t compliment you sooner on your entertainment virtues, but I spent a long weekend in Phoenix attending the Superbowl festivities.

Testing the ball pressure no doubt.

Circuit length is generally dictated by common pump size, available flow and head pressure. This in no way dictates loop length, which is dictated by by the size of the radiant panel serving a specified zone. It is convenient to CAD with even loop length in a single zone since balancing takes time and real experience, but is by no means necessary.

To assure an even gradient across a single zone panel it is the temperature differential that is important.

It must get confusing copying from a book...

"but I spent a long weekend in Phoenix attending the Superbowl festivities."

Like to brag like the OP I guess...

Chris

Really Badger…so you select the pump before you accomplish the HR design. Does it happen to be the pump that you get the biggest commission? Sorry, I have never been a “catalog designer”… Real HR designers first design the PEX layout to provide the required upward heat flux using the minimum supply temp to maximize heating system efficiency and minimize customer operational cost. Then they select the most efficient pump that will provide the required flow rate through the circuit design. Your approach is brilliantly simple, LOL!

ChrisJ, no not bragging...my team lost embarrassingly and heartbreakingly badly...sigh...

Living in RI most of us are Patriots fans... That's all I have to say about that..

ChrisJ in RI

OK, I got distracted last winter just finishing the basement up, and watching that 120" projector. It's raining today, and nothing to do so I am following up on the questions. Total basement Sq Ft = 1535 sq ft 4 zones, unfortunately can only read a few numbers and only 1 circuit with total length (1000-755) 245'. Our house is Geo Thermal so we're 100% electric (including water heater) however I do have gas (haha). From reading I think I would like to replace the 8 year old electric water heater with a high efficiency gas unit (do not have flu) with one that has separate loop for flooring. Assume it's cheaper to use gas for hot water and will not have to add separate heat source for flooring. So, with limited information available where do I go?

Two months and no feedback. Fall is around the corner and would like to get the plan in place. Maybe a radiant heat engineering company to do a design analysis?

bumped up, still looking for input for next steps