Incorrect (??) Hydronic Floor Piping

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opie

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I am looking at the system in the picture below. Bought a house with it installed 10 years ago. The previous owner (not original) admitted the system was not very good.
I think I have identified the problem but would like anyone's confirmation or another opinion.
Here's what I think.
Looking at the pic:
There is a EB-WX-27 electric boiler just to the right with a pump in-line to the upper pipe (supply).
I suppose the installer called this the primary loop. The bottom loop is the return to boiler.
Then he piped 8 zones out of this upper supply pipe to PEX underfloor heating.
He returned the 8 zones back to each zone's Taco circ pump, and then into the return loop pipe.
Without debating the position of the zone pumps in the return, it seems to me that he has confused his thinking about primary/secondary correct piping.
Because the supply to the zone is off the primary loop supply and the return is to the return loop, there is hydronic coupling that invites hot water flow through the zone piping even with the zone pump off.
Previous owner's comments about poor perfomance, and my own experience this season so far confirms that all zones get heat even without their zone pumps on and only one zone calling and that 1 pump on.
His mistake, I think, is that this system may have worked if he used a correct piping method of primary/secondary, meaning the supply and return taps to the zone were 6 inches apart on the primary loop.
If that 6 inch was observed then the zone(s) without a pump on would be hydronically de-coupled from the primary loop and supply water would bypass that zone completely.
This piping that exists in the pic might work if valves were installed in each zone loop, but that is time and expense. I can only guess that the installer was trying to improve the system, thinking if zone valves are good then zone pumps are better. But that turns out to be wrong, I think, because the zone pumps pass water even when off.
All opinions welcome.

IMG_5549.jpg
 

opie

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Yeah, "ghost flow", as shown in link, is scary and wrong. I may very well put in one or more Mitsubishi split systems as my bill last month was $500 ($0.21/kwh). This month the utility is kind enough to go to $0.13. But even then I could pay for a heat pump or two in two years I bet with the savings. Hydronic underfloor may be the Cadillac of comfort but I need to buy groceries also.
 

Mitchell-DIY-Guy

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Heating ANYTHING with electricity is going to be extremely costly. Whether you have electrical strip heaters as backup in your heat pump, electric baseboard, or an--goodness gracious--electric boiler, the cost to heat that water or air is going to be the costliest route.

With a lot of research and consultation, including some of that being paid consultation, with the help of my car wash supplier I engineered a 7 zone de-icing and snowmelt system for my home in 2009 (in Michigan). Using some fundamentals learned from the car wash business, we applied them to a residential driveway. Some of those fundamentals were: on average, about 180' per loop or zone. About 100K BTU per each 320 square feet. Circulating the entire fluid content in one minute. Careful design and placement of the loops.

At the car wash I owned, it was rather simple: we had a 500K BTU boiler, and a 30GPM pump, pushing through 1.5" copper manifolds to zones using ½" PEX. In a residential environment this wasn't possible for a number of reasons. First, I had no space in my garage for a 500K BTU boiler. Second, I didn't want anything called a "boiler" at home (>199,000BTU) since that involves all kinds of different permits and contractors and state boiler inspections blah blah blah. Lastly, no way did I want to upsize the gas line to my home.

That required the use of a tankless water heater to use as a heat source. At the time, 2009, the ONLY brand that would allow recirculation w/o voiding the warranty (i.e. robust enough) was a Takaki. I installed the largest they made--199K BTU. That however, would only flow 5 GPM, but the 7 zone loops, containing over 1,200 feet of PEX, needed to flow 31 GPM. The solution to that dilemma was this thing known in boiler-speak as "primary loop - secondary loop piping". The key words to that (if you read into that link you posted, @opie) is the carefully spaced Tees.

The secondary loop was with the manifold and the zones, and was pumped at 31 GPM through the zones. The primary loop was through the tankless heater. they two loops met at the Tees. Attached is a diagram of what one of the consultants came up with. The differences between that picture and what we eventually did was we used a larger Takagi TK-3 instead of the TK-Jr. We also used custom made full flow manifolds; those stainless steel ones shown don't have full flow. Though it's not shown in the image, our PEX in the concrete was ½" ID which was ⅝" OD.

It doesn't differ too much from a radiant heat system other than the BTU requirements. While I lived with the 199K Takagi, in retrospect what I really needed for a "perfect system" was about 300K BTU; that would only be achieved with two heaters. Overall, I was pretty satisfied with the system.
 

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Twowaxhack

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Heating ANYTHING with electricity is going to be extremely costly. Whether you have electrical strip heaters as backup in your heat pump, electric baseboard, or an--goodness gracious--electric boiler, the cost to heat that water or air is going to be the costliest route.

With a lot of research and consultation, including some of that being paid consultation, with the help of my car wash supplier I engineered a 7 zone de-icing and snowmelt system for my home in 2009 (in Michigan). Using some fundamentals learned from the car wash business, we applied them to a residential driveway. Some of those fundamentals were: on average, about 180' per loop or zone. About 100K BTU per each 320 square feet. Circulating the entire fluid content in one minute. Careful design and placement of the loops.

At the car wash I owned, it was rather simple: we had a 500K BTU boiler, and a 30GPM pump, pushing through 1.5" copper manifolds to zones using ½" PEX. In a residential environment this wasn't possible for a number of reasons. First, I had no space in my garage for a 500K BTU boiler. Second, I didn't want anything called a "boiler" at home (>199,000BTU) since that involves all kinds of different permits and contractors and state boiler inspections blah blah blah. Lastly, no way did I want to upsize the gas line to my home.

That required the use of a tankless water heater to use as a heat source. At the time, 2009, the ONLY brand that would allow recirculation w/o voiding the warranty (i.e. robust enough) was a Takaki. I installed the largest they made--199K BTU. That however, would only flow 5 GPM, but the 7 zone loops, containing over 1,200 feet of PEX, needed to flow 31 GPM. The solution to that dilemma was this thing known in boiler-speak as "primary loop - secondary loop piping". The key words to that (if you read into that link you posted, @opie) is the carefully spaced Tees.

The secondary loop was with the manifold and the zones, and was pumped at 31 GPM through the zones. The primary loop was through the tankless heater. they two loops met at the Tees. Attached is a diagram of what one of the consultants came up with. The differences between that picture and what we eventually did was we used a larger Takagi TK-3 instead of the TK-Jr. We also used custom made full flow manifolds; those stainless steel ones shown don't have full flow. Though it's not shown in the image, our PEX in the concrete was ½" ID which was ⅝" OD.

It doesn't differ too much from a radiant heat system other than the BTU requirements. While I lived with the 199K Takagi, in retrospect what I really needed for a "perfect system" was about 300K BTU; that would only be achieved with two heaters. Overall, I was pretty satisfied with the system.
We don’t have cold winters so a heat pump works well. I’ve only used heat 2-3 times this year and it’s almost December. Just doesn’t get cold and stay cold here.

You guys up north deal with weather we typically never get.
 

opie

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Twowax, enjoy your location!!!
Mitchell,
I assume you used a thermostat(s) on top of the slab covered with insulation to get slab temperature. My question is, what setpoint of slab temperature did you set? What differential did you set between heat call/ not heat call? (500,000 btu, wow..... I think that is 146.5 kw in electric equivalent.
Opie
 

Mitchell-DIY-Guy

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We had a slabstat buried just below the surface; turned the heater off but kept the circulation pump going. Set for 36 degrees. Driveway was >60 tons of concrete so fine control wasn’t possible. It only turned off under rare circumstances. Temperature movement on 60 tons of concrete was slow. Slab was 5” of concrete poured over a 1” layer of foam, over a 6” pea stone base…

The system itself was only turned on manually when snow was imminent. It ran in 6-hour cycles. Some winters worse than others. If it snowed and it was below 15 degrees, uncommon except in a polar vortex, I couldn’t get enough heat into the slab…thankfully it generally snows only when in the 20s and higher.

A snowmelt system and or de-icing system outdoors has different controls than indoor radiant heat.

@Twowaxhack this commentary clearly isn’t for a southern plumber with little need for this kind of work.
 
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Twowaxhack

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We had a slabstat buried just below the surface; turned the heater off but kept the circulation pump going. Set for 36 degrees. Driveway was >60 tons of concrete so fine control wasn’t possible. It only turned off under rare circumstances. Temperature movement on 60 tons of concrete was slow.

A snowmelt system and or de-icing system outdoors has different controls than indoor radiant heat.

@Twowaxhack this commentary clearly isn’t for a southern plumber with little need for this kind of work.
Yeah, I wasn’t planning on installing any ice melt systems around here. Especially with global warming 🤣
 

opie

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Mitchell and Twowax,
I am in eastern NC, but the house we bought with the hydronic underfloor is way up north. (and on edit.... from my first post, it should have read:
Bought a house recently with this hydronic underfloor heat that was installed 10 years ago when the house was built.)
 
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Mitchell-DIY-Guy

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(500,000 btu, wow..... I think that is 146.5 kw in electric equivalent.
Opie
My car wash (I owned one from 2002-2008) had a 500K BTU floor heat boiler, and a 1.2M BTU boiler for hot water, using an 80 gallon storage tank. I also had a 3000 GPH RO system to generate spot free rinse water, a 200 gallon RO waste water recovery system. I had a miniature plate heat exchanger (about 4 x 8 x 1") to create a separate heated trough running in the attic over the bays to keep the lines from freezing. I had a 2" water main coming in, and often used 100,000g of water per month. My touch less used a 25HP motor and could blow at 1200 PSI at astounding volumes. Everything in a car wash is oversized, and chosen for reliability over anything else.
 

Twowaxhack

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There was a plumber on Plumbingzone professional forum that specialized in piping car washes. ILPlumber out of Illinois.

He said it was very profitable and a ton of piping
 

Mitchell-DIY-Guy

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There was a plumber on Plumbingzone professional forum that specialized in piping car washes. ILPlumber out of Illinois.
He said it was very profitable and a ton of piping
Owning a car wash is a good business if you don't have to have any bank loans, and if you are a plumber or electrician and or feel comfortable with both. You'd go broke if you had to pay a plumber or electrician for maintenance. I did most of my own maintenance but relied on a local car wash support company. Their tech knew more about plumbing than most plumbers and more about electricity than most electricians, and did exceptionally clean and neat work. We got along great. He was worth every penny I paid for his services.

As for "piping" there was a bit of course, mostly with the hot water systems. All the distribution stuff with the soaps and chemicals was all PE tubing, and you really needed to learn how to do all that yourself. Yes there was literally miles of tubing: all color coded ¼" poly lines delivering premixed chemistry to the bays...and some high pressure lines. Lots of check valves, foam generators, pumps, unloaders, etc. On the electrical side, all the motors were 3 phase, run through electromechanical contractors (relays). I had a 25KVA transformer on a pad in the parking lot to feed all of this stuff. I had a 7.5HP compressor since compressed air is necessary for foam generation and operation of pneumatic valves. Every day something needed attention and if you knew what you were doing it was fun. You had to constantly check on everything since you never knew when a line was going to blow. I was constantly rebuilding high pressure valves, pumps, etc. Never ended.

Most customers were respectful, and honest...as long as things were working. Some people would start destroying things if they lost a quarter...so the best thing to do was have ultra-reliable equipment and you needed to have redundancy and backup (spares for EVERYTHING onsite) else you'd be fighting vandalism. I had almost none of that because I took care of the customers and the equipment.

One of the first things I did, after a few months of experience, is get rid of all brass and copper fittings in the chemical lines, and replace with stainless steel. The soap would eat through the brass and copper.
 
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