Advice on manifold placement

Rice

Hi. I built my own house entirely and the one thing I sub out was the heat. It's subfloor radiant. The problem is when the guy showed up with all parts . Got another 25% after the first 50% and the he vanished. I attempted it myself because money is tight and Christmas is close so using ingenuity and the books in each box. My issue is I can't find anyone to give an opinion if it looks close at all to being right. Any suggestions would be awesome. The other two manifolds are down at the zones they go with with 3/4 pex running to them witch I believe to be a mistake but not sure how big of one. Any help would be awesome

Ironman

Well...

Unfortunately, using a water heater for space heating is a poor choice and is not up to code since it does not have an ASME "H" stamp. At least it's isolated through the HX.



First how are you controlling the water temp to the floors? What type of floors? Wood? Slab? Both? What type of floor coverings? If you have wood floors were heat transfer plates used? How much tubing was installed? What size and what lengths?



Has a load calculation been done? What are the results?



As far as what I can see in the pics goes, the install looks neat and the piping looks correct except the radiant circ needs to be mounted horizontally, not vertical. But, without the above info, it's not possible to know if you have the sizes and components necessary.

Rice

Tryin

The water heater is 100000 btu designed for the radiant heat from radiantec. Granted I may of been misinformed. Floor is 3/4 advantage plywood and tile throughout. 3 zones. Two are (2). 300ft runs 1/2 pex. And center zone is 5 runs 300 ft 1/2 pex. Water heater set to 120 and water into mNifolds reads 120 and 105 on return. No load test done but house is real tight. Witch pump due I need to turn the bigger one? And my other concern is my bigger manifold is 15 ft away being feed with 3/4 pex. I don't believe that's big enough is there a rough guideline. 1" pex maybe.

Ironman

Internet Peddlers...

Have one main goal in mind: selling you their wares. They know that you're shopping other ones, so they try to find ways of cutting corners to make their price the most attractive. I'm surprised that they didn't try to sell you a Takagi tankless water heater. That's their usual m.o.



The larger circ on the right is the one that needs to be rotated so the motor is horizontal.



The remote placement of the manifolds should not be an issue as long as they don't require more than 4 gpm. Again, that's where a load calc is essential for designing a system. Piping sizes are governed more by gpm than length in residential application, though both play a part. The 1/2" tubes in the floor produce more head ( resistance to flow) than the 15' of 3/4" feeding the manifolds. The only way to know how many gpm the manifold needs is by knowing the load.



Advantek is a plywood, but that doesn't tell us if you have heat transfer plates under it. They are crucial to get enough btu output from the floor.



You should set you water heater to at least 140* and let the domestic mixing valve temper it back to about 125*. This will help reduce legionella which is in all fresh water. It will also get you some more btu's to the heat exchanger to go to the floors. Then install a thermostatic mixing valve on the radiant side and set it for 120*. The reason for this is to get you some more horsepower to the floor and lower its delta T which is 15* now. You want it to be 10*, but it looks like you have a 5x12" 20 plate HX which is too small to transfer 100k btu's when the supply temp is the same on both sides. Raising the supply temp from the water heater will help this.

Rice

Thankful

I have plates I bought off craigslist I bought 600 of em the are 16" by 2' . I can put them up . I already rotated the pump horizontal and can get enough flow on my big manifold for it to even read. I'm going to replumb the feeds in the morning with 1" copper feed and I'm hoping (suggestions) I can get away with 3/4 on the return or maybe 3/4 for all of it. I'm going to see if it pumps better with the pump turned in the am. Thanks for helping me out.

Ironman

1" Mains

Sorry that I didn't notice that you have 3/4" mains. You definitely want 1" on the mains.



What are the models of the circulators? They may be too small.

Rice

Feeds

006-st4 1/4 hp and a 1/8hp. 3/4 pex feeding it now would 3/4 copper be up for it

Ironman

Model?

What's the model of the radiant circ?



There's almost no difference in the capacity of 3/4" pex vs cu. as long as the pex has minimal fittings.

Rice

Btu

House needs 72000 btu. It's 1800 sqft roughly but last year I ran 3 quartz electric heaters from Walmart and the house stayed 70 and we had some bad cold snaps below zero I ran a 4th so worst case I thinks 1500watts times 4 heaters is 20000btu

Rich_49

May I

inquire to who informed you that an 1800 foot square home that is tight would ever require 40 BTU /sq/ft ?  Unless you reside somewhere relatively sub arctic this is a hard number to accept . 

The 006 pump you have there , where is that pump or are they both 006's ?  The 006 is not capable of 72000 BTUs but may be enough pump for 20 K at 3.8 feet head or less .  Gentlemen , am I mistaken or is this circ pumping directly towards the Expansion tank ?  Rice , if this pump is in fact pumping to the right of these photos it should be moved to the other side of the expansion tank . I also don't see a backflow prevention device on the heating side of this arrangement and the pump is also pumping directly toward the pressure reducing valve . Rice , a backflow prevention device is required on this piping so nasty heating water that may have unhealthy things in it don't hurt you and yours . A good place to pipe that PRV to would be to a tee right under the air elimination and add the BFP right before the PRV .  I would also use a TACO Delta T circ instead of the one that is there since all zones are pumped by one device . When you get the right pump in there you may get a lot of velocity noise and be moving too much fluid for beneficial heat transfer to take place .  Check the direction of the pump on the heater side of the Heat exchanger also , does it pump to the bottom of the heater ?  It should , you want your supply water being taken from the top of the water heater where it is the hottest .  We will be here to further assist you .    Is your water heater set to 120 or is the mixing valve ?

  I would also like to say that you have done some very nice looking work here .

Rice

Thankful

The water comes in on far right through a back flow preventer and auto fill valve then through expansion tank and spirovent. Then it hits the pump then through exchanger, manifolds, returns through the circ switch things(lol) I felt like the electric valves and pump should be on the cold side to be less abusive on them. And yes on the water heater side the ports were labeled on how to pull the water out. It is at 140 on water heater now and 120 on mixing valve and putting a mixing valve in closed heat loop tomorow. I'm loving the feedback. I feel like good heat by Christmas is an option

Rice

...

The bigger pump is the 006 and the smaller one I forget the small is 1/8 hp and the bigger is 1/4

Ironman

Pumps

Rice,

The 006 is a 1/40 h.p, not 1/4 h.p. The 1/8 h.p. circ is probably a 009, which is a high head circ. It will make a lot of velocity noise if only one zone valve is open and all the flow is forced through two 1/2" loops. A flow velocity of over 5 ft. per second will cause pipe and component erosion.



I agree with Rich that one or both of these circ's are not sized correctly. Again, we need a load calc detailing each zone to be sure, but it appears that the 006 is too small to transfer enough heat between the water heater and the HX and the 009 should be replaced with a variable speed delta T circ.

Rice

Zones

Not sure if this is what u want but house is 30x60 zone 1 and 3 are identical I such they are two 300ft runs under the subfloor with carpet in bedrooms and runner pad above and the third zone the middle one is 5 300ft runs under tile. House passed energy star with 4 inches of spray foam and 26 inches of blow in in attick. Currently it's like 30 degrees outside and two 1500 watt heaters are keeping house 72. Everything is hooked and bleed and manifolds 1 and two when on together calling for heat show 120 degree water entering witch is what the water heater was set at during that time. It seemed to transfer the heat great but just lacked flow on the closed loop side.

Rice

Pumps

These are the pump covers

Rice

Pumps

Pump covers the 006 is on the domestic side

Rice

Pumps

I'm sure u already know this but here is the specs on the one in the heat circuit

Ironman

Pump curve

Based upon what you stated, you have heat loss of 72k btu's, 9 loops of 1/2" pex 300 ft long each.

To get 72 k btu's with a 10* deltaT would require 14.4 gpm / 9 = 1.55 gpm per loop. At 1.55 gpm 1/2" pex has a head loss of .04 x 300' = 12 ft of head. That's just the tubing in the floor; it does not include the manifolds, distribution piping or plate HX. That could very easily add another 6 - 8 ft of head, bringing the total head to around 18 - 20 ft.



According to the pump curve for the 010, it maxes out at about 10 ft. of head. That means it's not the correct choice. It's a high gpm, low head pump. Aka a flat curve circ. You need one that can handle a higher head and still give you about 14 gpm. I'd recommend the 013 delta T circ. It will vary its speed to match the number of zones that are calling while maintaining the desired delta T of 10*.



http://www.taco-hvac.com/uploads/FileLibrary/101-033.pdf

Rice

Progress

So the pump I have is mostly useless then. I will look up the bigger pump and also finish bigger lines to the other manifolds. My insulation for the floor joist is due to show up tomorow also. I let the system run today again and had zones 1 and 2 run after ten minutes I checked and temps in and out in zone one was 120 in and 110 out and .6 gpm zone two was 120 in and 105 out with just enough flow to make the gauge wiggle. Hopefully bigger feed and returns help a little and I will probably not be able to swing a pump till after Christmas. The basement is also like 55 not sure if that makes a difference. Thanks again for the help. Is this the right one

Steamfitter66

Stop what your doing and preform an actual

Heat loss calculation. You may be just fine with a 006. your actual load is probably 1/2 of the 72000.

Once you have an actual heat calc for each zone you can then see what your water temps and gpm need to be. Until then your wasting time and money.

My current projects in N Illinois include a shop at 21 btu sq ft, a house at 14 btu sq ft, a commercial building at 12 btu, and a retrofit at 27 btu.

If I used rules of thumb I would have oversized my materials wasting my customers money.

Rice

Heat loss

Not sure how to due this or if I am able. I'm assuming that a warm house to a specific temp, shut heat off and see how fast temp drop over a period of time based on outside temp.

Rice

Heat loss

I did three different heat loss calculators and they were all consistent around 52000btu

Rice

.

Last year I had during the coldest snap like -30 at night and -10 during the day 4 1500watt heaters running and that kept house 70. They did run constant but they did maintain the temp for the 5 day cold snap that's 6000 watts or 20000btu. So if I double that number to 40000 btu for safety that's what the calculators would give me if I could be more specific on the construction. My spray foam guy said with the 4 inches if foam in the wall and over 2 ft blown in attic, and good windows he said 25btu a square ft is a good reference

Ironman

100k, 72k, 52k, 40k, 20k ?

Those are the numbers that you've given for your heat loss. Which is right? Have you actually done a scientific heat loss calculation? I'm not talking about one of those little estimators like Pex Supply has which says " if you house is xxx number of square feet with average insulation, then you need xxx btu's". That's not scientific. And, I've seen it be off by 50%.



Rice, every bit of engineering and design in this trade starts with an accurate heat loss calculation. It's the foundation for everything. You don't double it or add a margin for error to it. You do it accurately.



There are several online heat loss calculators available that are simple and easy to use. You don't have to be a pro, you just have to input accurate info. SlantFin is a good one and it's free.



Please, hit your brakes, come to a complete stop and do an accurate heat loss. It shouldn't take more than a couple of hours (maybe less) to get the measurements and input the info. If you blueprints, you already have the measurements.



I'm guessing you'll probably come in somewhere around 30 - 32k btu's. But, no one can size your floor, piping, pumps, HX or anything else without the load calc.

Steamfitter66

Dont double to be safe

This is important to follow through carefully.

You want an exact number and the fudge factors are already built in to the calculations.

I use CDAM for radiant but slant fin is about as good and is accessible to home owners. http://www.slantfin.com/index.php/homeowners/ipadapp.

Please do it before asking any further questions , if your maintainer temps with 6000w on a design temp day the your heat loss should come in around 20 -25000 for the space your heating. you will need to add for basement and garage if they are heated.