feedback on hydronic plumbing plz

[skidoo]

This is my first attempt at setting up an infloor heat setup,
With a lot of searching and reading and weeding I think my plumbing is ready to be finished up.
So I have a 15kw modulating boiler feeding 4 loops of 230-250 ft each.
Hot water exits the boiler via 3/4" copper pipe and feeds into a taco air separator that has an expansion tank threaded on the bottom (not shown).
Then I have 2 hose attachments for filling and bleeding, with a 1/4 turn ball valve in between.
Then it feeds into a grundfos alpha pump.
My plan is to use an automotive style coolant flush machine to fill the system with a 30/70 propylene/ distilled water mix from the right side hose connection, close the ball valve and bleed the air.
Then once fluid starts to expel from the other hose, run it into the supply bucket so that the fluid will recirculate and bleed out the air.
Sorry for the book, but feedback on the plumbing before I finalize it, thanks!!

 

[anthony666]

expansion tank

 

[anthony666]

.... etx 30, is probably what you spec'd out .. 4.5 gallon capacity .. that's near 40 pounds of water, unsupported except by threads go into the wall kettle .. bring that line back against the wall and remote the tank on some pex or something and support that weight

there's a check valve in that pump ?? think about whats gonna happen when the system is off and stagnating, releasing dissolved gases .. where is air gonna collect ?? maybe relocate your fill and purge set up south of the pump to facilitate getting it out

also i hate single pump systems, they assume that the flow rate necessary for the boiler to function and the flow rate for the floor are the same ... they seldom are

 

[skidoo]

.... etx 30, is probably what you spec'd out .. 4.5 gallon capacity .. that's near 40 pounds of water, unsupported except by threads go into the wall kettle .. bring that line back against the wall and remote the tank on some pex or something and support that weight

there's a check valve in that pump ?? think about whats gonna happen when the system is off and stagnating, releasing dissolved gases .. where is air gonna collect ?? maybe relocate your fill and purge set up south of the pump to facilitate getting it out

also i hate single pump systems, they assume that the flow rate necessary for the boiler to function and the flow rate for the floor are the same ... they seldom are

Thanks Anthony,
So I was going to build a bracket that attaches to the horizontal stud near the bottom flange of the pump to support the pump and the expansion tank.

The pump has one of those plastic check valves on the outlet, is that good enough?
I was thinking the fill/bleed as high as possible, but pretty easy to relocate downstream of the pump if that is better.
Thanks.

 

[anthony666]

Thanks Anthony,
So I was going to build a bracket that attaches to the horizontal stud near the bottom flange of the pump to support the pump and the expansion tank.

better off to put it directly under the expansion tank so it's not hanging by the threads .. cut out a hole the size of a coffee cup so you can fool with the schraeder valve if necessary

The pump has one of those plastic check valves on the outlet, is that good enough?

yes .. but the issue isn't the check valve, it's that if air comes out of suspension it will be trapped with no way out but all the way back through the piping and the boiler

I was thinking the fill/bleed as high as possible,

there's gonna come a day when you need to work on the system .. if the fill/purge set up is at the top how are you going to drain the water out ??

you're welcome bud, stay warm

 

[skidoo]

Hi,
So I got everything plumbed and filled, bled the air out into a clear container of water until no bubbles only fluid came out. Ended up removing the 1 way valve on the outlet side of the pump.
Fired it up last night at about 5pm, supply temps are 110F and return temps are currently about 46F.
My return temps are still pretty cold but the slab is about 8 degrees warmer than last night, outside temp is colder by about 10f then it was last night.
My question is how accurate is the flow meter on a grundfos pump or for that matter, the plastic flow meters on the manifold? The reason I ask is bacause even with the pump cranked up to the highest flow, the pump only indicates 1-2GPM and according to the spec sheet it should flow 6-7gpm at 8ft head.
Maybe I should install a pressure gauge between the pump and the manifold?
Pump runs quiet, which I assume means it is not cavitating, and I know there is flow because with the pump cranked up all the way, my boiler command goes up to 60-80%

thanks very much for the help guys! Could not have even got this far without input and information on this site.

 

[stingry]

Hi,
So I got everything plumbed and filled, bled the air out into a clear container of water until no bubbles only fluid came out. Ended up removing the 1 way valve on the outlet side of the pump.
Fired it up last night at about 5pm, supply temps are 110F and return temps are currently about 46F.
My return temps are still pretty cold but the slab is about 8 degrees warmer than last night, outside temp is colder by about 10f then it was last night.
My question is how accurate is the flow meter on a grundfos pump or for that matter, the plastic flow meters on the manifold? The reason I ask is bacause even with the pump cranked up to the highest flow, the pump only indicates 1-2GPM and according to the spec sheet it should flow 6-7gpm at 8ft head.
Maybe I should install a pressure gauge between the pump and the manifold?
Pump runs quiet, which I assume means it is not cavitating, and I know there is flow because with the pump cranked up all the way, my boiler command goes up to 60-80%

thanks very much for the help guys! Could not have even got this far without input and information on this site.

You are expecting too much from your pump flow wise. You have way more than 8' of head loss. Just the head loss thru 250' of 1/2" PEX at 2 GPM is about 13', this plus the loss thru the other plumbing and the boiler is restricting how much flow your pump can provide.

The proper way to size a circulating pump is to do a heat loss calculation and use this to calculate what your flow needs to be thru the system. With an approximate flow established, you then need to calculate your head (pressure) loss and then select a proper pump based on its pump curve.

Cheers
Steve

 

[skidoo]

You are expecting too much from your pump flow wise. You have way more than 8' of head loss. Just the head loss thru 250' of 1/2" PEX at 2 GPM is about 13', this plus the loss thru the other plumbing and the boiler is restricting how much flow your pump can provide.

The proper way to size a circulating pump is to do a heat loss calculation and use this to calculate what your flow needs to be thru the system. With an approximate flow established, you then need to calculate your head (pressure) loss and then select a proper pump based on its pump curve.

Cheers
Steve

Hey Steve,
From what I could figure, my 900sq ft slab should need 50,000btu so I think I need 5gpm/4 loops for 1.25gpm per loop. So thats how I came up with the 8ft head. Does this make sense? Anyhow I was thinking of going to pick up a pressure gauge to tee between the pump and manifold... thanks

 

[Highbeam]

You are expecting too much from your pump flow wise. You have way more than 8' of head loss. Just the head loss thru 250' of 1/2" PEX at 2 GPM is about 13', this plus the loss thru the other plumbing and the boiler is restricting how much flow your pump can provide.

The proper way to size a circulating pump is to do a heat loss calculation and use this to calculate what your flow needs to be thru the system. With an approximate flow established, you then need to calculate your head (pressure) loss and then select a proper pump based on its pump curve.

Cheers
Steve

Boo. He obviously has more than one loop of pex so the gpm through each loop is a fraction of what the pump is flowing.

You have the pump curve for the grunt. Now add up the head loss for each component including the boiler, near boiler piping, spirovent, etc. to find your place on the pump curve. See if you are in the efficient zone.

 

[stingry]

Boo. He obviously has more than one loop of pex so the gpm through each loop is a fraction of what the pump is flowing.

You have the pump curve for the grunt. Now add up the head loss for each component including the boiler, near boiler piping, spirovent, etc. to find your place on the pump curve. See if you are in the efficient zone.

You're right. My Bad, shouldn't post first thing in the morning!!

 

[sands35]

Not sure if it was captured yet - but your pressure relief needs to vent to less than 4" of the floor.

 

[skidoo]

Not sure if it was captured yet - but your pressure relief needs to vent to less than 4" of the floor.

Do you mean the pressure relief on the upper left side of the boiler? i assume this is a safety issue so that in the event of a pressure spike, the scalding liquid won't spray everywhere?
Thanks

 

[skidoo]

I picked up a pressure gauge, and with 13psi in the system, there is 18 psi between the pump and the manifold, so am I correct in assuming there is 5psi back pressure or 11 ftf head? With no pressure in the system and the pump on high, there is about 4psi between the pump and manifold?
Either way, those cheap plastic flow meters indicate zero flow, and the digital readout on the pump shows 1 to 2 gpm. Seems to work, but just wondering. thanks.
floor is now 67f, outside temps are 23f or -5 f

 

[anthony666]

monsieur skidoo, let's see the finished product bud

those flow "meters" are flow indicators at best .. as long as you put them the right way they should show something .. they go on the hot side, mess with the valve on the cold side to adjust them .. bypass the tt terminals to make a heat call .. turn all of the valves off and then turn one on at a time and adjust it till you get them all equalized out

also, i recall reading your strategy for filling the system .. doesn't sound like a good way to get all the air out

 

[Highbeam]

Yes a picture of the finished system please. I liked the simplicity and the single pump.

 

[sands35]

Do you mean the pressure relief on the upper left side of the boiler? i assume this is a safety issue so that in the event of a pressure spike, the scalding liquid won't spray everywhere?
Thanks

I can't tell from your photo. Somewhere you need a pressure relief valve. It needs to be vented to the floor so, yes, somebody doesn't get sprayed with scalding water.

It is a code requirement.

 

[skidoo]

pics as it is now.
Floor thermostat is set at 67. What are you guys using for a target slab temp?
I also have the outdoor sensor which I haven't wired yet.

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ok so i still need to build the support for the expansion tank and put an extension on the blowoff (?) valve.
I filled it through the right side green garden hose with a coolant pump and the ball valve closed. The left side green hose was stuck into the pail that the coolant was being drawn from, so I just ran the pump and opened closed the pex loop valves until no more air bubbles came out of the left hose.
Then I put a ball valve on the highest part of the boiler with a 3ft piece of braided steel line and bled it into a bucket (mounted on my custom aluminium stand... ok step ladder) until no air came out of it.
Then I closed the boiler ball valve, the left ball valve leading to the pail and opened the 3/4 ball valve and the kept on pumping fluid into the system until I had 13psi pressure in the system. Then closed the supply ball valve and powered up.
Is there a better way I could have bled the air out? thanks for the help guys, we ain't done yet. Now for the fine tuning.

 

[LsFarm]

Your target slab temperature depends on your target room temperature and your level of insulation in the room.
67* slab temp will usually result in about 60* room temperature AFTER everything in the room is up to temp. Bring in a cold car, and it will take a while for the room temp to recover.
I keep my home floor heat no warmer than 77*, it's plenty to get the house up to 71-72*. The house has R27 walls, and R55 ceilings.
In my shop, I keep the floor at 50-55* and take whatever room temp I end up with, and when I'm out in the shop to work, I augment my working area with portable radiant heat. If I'm going to be in the shop all day, I use a waste oil heater to get the shop up to 60* or so.

If your slab has warmed up overnight, then I'd say you are OK, even though you don't show much flow rate through your system. You could try a bigger pump to see if you get more flow and better heating, but I don't think you need more flow. Unless your return water temp has not reached the 67* slab temp, then you might need more flow for colder weather.

Lsfarm

 

[anthony666]

kk .. sounds reasonable .. that lime koolaid is not automotive antifreeze though, yea ?? dig the custom stand button it up and build that bracket

so how is the temp in the shop and how fast is the little wheel spinning on the hydro meter ??

 

[skidoo]

Hey Anthony,
I see you are also in Ontario, so Hydro one has a cool little feature on their website where you can graph electrical usage in kilowatts or dollars.
The first 24 hour period cost me 12 bucks to get it to 20 degrees c. Original slab temp was 0c and I just ran it 24 hours on high speed pump with the set point at 110f
The next 24 hour period cost 6 dollars to maintain, and the outside temps were -7
The next 24 hours was about 4 dollars, but I still just had it running 24 hours.
This morning i put a timer on the thermostat to be "live" during off peak hours (7pm-7am) and then be live for 5 hours during mid peak hours (11am-4pm)
Should cut costs, because peak hours are 13.5 cents per kw vs 7.5c for off peak hours.
This weekend I'm also going to get the outside temp sensor wired in, then its time to pay attention to the toys!!
this is the glycol I used.
thanks again for all your help!!

 

[anthony666]

straight along highway 7 .. we're practically neighbors

most of my customers that i cant talk out of using hydro end up doing the off peak timer trick .. as long as there are no ground water issues it works mint mate

don't forget the bracket