Installing HTP-UTF 80

hot_rod

Yes the tanking maintained at a temperature adequate to provide the DHW you need, I'd start with 140. The radiant zones would be mixed with a thermostatic valve, the least expensive method. Or a motorized valve, or injection mixing, if you want the heat zones on ODR.

I have not used one, but the Taco 3 way electronic valve might be ideal for the mix down?

A couple options from Idronics 17
Thermal Storage In Hydronic Systems

NY_Rob

Sorry to add this, but keep in mind that HTP recommends flushing the HX every 2yrs or so with a descaling agent. It's easy at this point to add valves that will let you do that vs. adding to an installed system.


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https://www.supplyhouse.com/Webstone-40614-1-Pro-Pal-Full-Port-Forged-Brass-Ball-Valve-w-Hi-Flow-Hose-Drain-Reversible-Handle

NY_Rob

^ Just noticed in one of your photos that you're not using the bottom left supply connection, so you only need just one valve there since you have a ported valve on your circulator flange on the return.

Just connect the descale pump outlet to the new bottom left supply side valve and drain into a bucket from the hose drain port on the pump flange.

Ironman

DAVIDSEIDEL said:

Ironman ,

Would I need a third pump? Controlled by the tekmar 356? Getting very frustrated.

Thanks,

David

Don't fret David; your near the finish line. It's better to make corrections now than after its running.

The issue with heating a slab is its mass. It's a huge rock that takes a long time to heat up, but conversely it takes a long time to cool. It's called the flywheel effect. The problem with just letting a thermostat and/or a thermostatic mixing valve control it is if the SWT is too warm, the slab will continue to give off its heat for many hours after the stat is satisfied. It's not unusual in that scenario to see the area overheat by 8 - 10* or more. The solution is to use ODR which will vary the water temp based upon outdoor temp. If you get the ODR curve dialed in correctly, the thermostat is almost unnecessary; it just becomes a high limit. I've got a radiant job next door that we did about seven years ago and the only thing controlling it is a Tekmar 356 with no thermostat. My neighbor tells me that it stays a constant 68* throughout the heating season.

The two examples shown in the diagram are either variable speed injection mixing with a Tekmar 356 and an additional pump or a smart valve like Taco's I series. The materials will run about the same either way, but the VSIM gives the added benefit of not interfering with the flow rate in the slab. The mixing valve will add more resistance to flow (head) which must be calculated in to the circuit.




I see 11 loops between the two manifolds. The best flow rate you can realistically expect is about .7 gpm with 300' or less per loop. That means about 8 gpm total. At that flow rate, the 1" I series valve with add at least 7 ft. of head to the circuit which is too much for the Alpha circulator. Therefore, the Tekmar VSIM is the better choice.

hot_rod

Often .5- .6 is max suggest gpm for 1/2" pex, so .5 per loop would drop head and the Alpha may work for you, interpolating 5 gpm on the chart above from Bob.

Ironman

hot rod_7 said:

Often .5- .6 is max suggest gpm for 1/2" pex, so .5 per loop would drop head and the Alpha may work for you, interpolating 5 gpm on the chart above from Bob.

Good point. It's gonna depend on how long the loops are. If they're 250' or less, you may see closer to the .7 gpm with the circulator at full speed. Add in the resistance of the I series valve, and you may be at .5 gpm which is fine.

Ironman

Oddly enough, the 3/4" union valve has the same rating as the 1". It's probably the same body.

DAVIDSEIDEL

I worked my butt off trying to get the piping just right.
What would be a better option at this point? Re-pipe so I can add a injection pump with close spaced Tees or just add a small indirect DHW heater tank? I have the other connections available on the HTP.
With the later I can fine tune the central heating system to work very efficiently with the buffer tank. Not use the TurboMax DHW ports. Then keep the DHW at 140 and it wont effect the CH temps.
With the re-piping and injection, I feel like the whole system is a compromise. Or......an I over thinking this?

Ironman

Are you gonna control both manifolds from only one stat?

DAVIDSEIDEL

I went with two manifolds because of price. The 2 missing zones yet to be installed are bonus room above garage. Only a 20 degree difference because garage will be at 50 degrees. That staple up alum reflector wont need as much thermal heat as the slab. A 13 loop manifold was $$$$$
One stat for the manifolds, 4-5 zones.

DAVIDSEIDEL

One thing I have learned about being my own general contractor is finding good, reliable help is very hard. Especially finding knowledgeable contractors. Eye opening to find out that 75% of installed mod cons are not using the ODR. That is sad. I can only imagine what would be installed if I did not know anything.
I have learned a lot from you folks and I am very thankful I found this site.

Ironman

The slab won't need any buffer because of its mass, but small staple up zones will. However, because of its low mass, the staple up doesn't require ODR.

I'd connect the slab directly to the boiler and let the boiler's ODR curve control the SWT to it. Then connect the staple up Tee'd off of the indirect's nipples like you've got it. Set your indirect to be controlled by its aquastat at about 125* and wire that back to the domestic terminals on the UFT.

Any thermostats for the slab would connect directly or indirectly to the "TT" space heating terminals on the boiler. You'll need a pump relay if there's more that one stat.

Any thermostats controlling the staple up micro zones would need to go to a pump relay like a Taco SR5-- (number of stats). The relay would then activate the pump for the micro zones.

This will work fine and you'll only have to do a little repiping.

DAVIDSEIDEL

I am trying to understand this. From previous posts, I thought I needed the buffer tank because of too small of zones (garage, 2 loops), (master bdrm, laundry, bdrm, 4 loops), ( bonus room, 2 loops).
The buffer would stop short cycling.

Ironman

Your slab is the largest buffer possible. It doesn't need to be connected to the buffer tank. It can connected straight to the boiler. It's the low mass staple up micro zones that need to work off of the buffer tank.

Gordy

The uft 80 can modulate down to 8k. So any zone requiring less btu output than 8k will short cycle the unit.

So when deciding on zoning size, that needs to be thought about. Also 8k at design temp is not going to be most of the heating season.

Fast responding panel designs with low mass are great for reaching set point faster, and control from over shoot. But lack the buffering high mass panels provide.

Gordy

The whole premise of the buffer tank is to allow the boiler to charge the tank with out short cycling. Then the buffer tank provides the btus to the low mass panel zones.

Gordy

Going back to your original post your total manual j is 36 k. So divide by 8k gives you around 4 zones to meet the 8k minimum of the lowest modulation. It doesn’t mean you can’t have more than that it just means you will short cycle with smaller loads so the buffering helps this issue.

DAVIDSEIDEL

Changing to Primary system to the slab. Extra ports on the HTP UTF 80 to the Turbomax for DHW. Can the Caleffi Dirtmag be in either line before the pump? Primary pump or TurboMax pump to tank, any preference or does it make no difference?

SuperJ

Ideally you want the mag separation before your ECM pump since it has strong magnets inside that attract ferrous debris. You don't need an ECM pump for the turbomax tank since it will be constant flow, but 3 speed ECM pumps use substantially less power even in constant speed applications. You might be able to get away with a single pump, if you have a 3or4 way diverting valve on your turbomax switching the flow from the infloor to your turbomax whenever it needs some heat.

If you are going direct to floor, make sure you have the circuit valve end switches wired properly so the boiler won't fire before the circuit valves are open. This means your thermostat should open the valves, and the end-switches should start the boiler. Boiler should start the pump. Since you have multiple infloor zones you probably want to use one of the constant pressure settings on the Alpha pump (probably med/hi). If you have a smaller zone then you could leave it's end switch disconnected so that it only heats when one of the other bigger zones is also calling. If you have your ODR setup properly you should almost have a continuous call for heat without overheating the space.

Anecdotally, the 4-way valve (in the chart above) has a super low pressure drop. But any sort of mixing/injection ultimately means that you are leaving some efficiency on the table, since you are technically overheating the water and then cooling it again. Setting up a direct piped arrangement to your in floor, and a DHW priority arrangement to the turbo max seems like the best compromise for simplicity and efficiency. I'm assuming you are just going to run all the in floor at the same temperature.

It would probably good to post a diagram of your intended approach, to avoid anymore changes that require repiping.


Turbomax pressuredrop chart. (it's pretty low).

DAVIDSEIDEL

Got the boiler running the Sunday before Christmas. All is working very well. No leaks. I am just running one stat on all loops temporarily. I have a question about the pressure gauges on the supply and return. It is sometimes stable around 12 psi, and sometime both gauges bounce somewhat. Any reason why the gauges would bounce / wiggle about 1 psi?
Thanks, David

GroundUp

Where are the gauges? Unless located at the point of no pressure change where the expansion tank should be, they will fluctuate when the pump runs

NY_Rob

My gauges will do that occasionally under high load, I think it's due to the design of the UFT's Heat Exchanger. My system is in it's third winter, I still hear an occasional "perk" at high fire.

DAVIDSEIDEL

They are installed right at the manifold.

NY_Rob

^ when the needles are jumping... do you hear any of the percolation "pings" I mentioned above?

What's the GPM rate on the Alpha when it's happening?

Is it happening only at high fire rate?

Check the pressure of your expansion tank too.

DAVIDSEIDEL

Thanks for the responses.
I do not hear any pings or percolation.
The Alpha pump runs at 5 - 6 GPM.
It is high fire rate....... I believe. I will verify.
I Will check the expansion tank pressure.
Basically, I set the temp of the boiler at 140, ran all loops open, control off one thermostat so I could get it going and stop oozing $$$$$$ on the temp electric heat I had set up.
When I get the house closer to done, I am sure I will have questions on setting up the turbo max, zones, ect.
Still have to check the combustion with an analyzer as well.
David

DAVIDSEIDEL

Another question.
My co-worker thinks I am crazy for not running glycol in the system. I used just water and conditioner/inhibitor. He said he would be worried about freezing. It is a house, not a cabin.
And, I will be able to monitor if gone for week or two. My thinking is it would take a long time for that slab to freeze.......or am I crazy for not having glycol. I am looking at the heat transfer and pumping efficiency of water as an advantage. What would you do?

NY_Rob

If it's happening at high-fire it could be due to the fact that your CH water is still relatively "new" and still has lots of entrained air in it. If you have enough flow through the HX for the amount of BTU's the boiler is producing the surging should eventually subside once the water has been heated many times and the air separator has removed all the micro-bubbles.

That's one thing with mod-cons... it takes a while to remove all the entrained air from the CH water as you hardly ever get the water hot enough to remove every last bit of air like in a standard atmospheric boiler that heats the CH water to 180-190F every time it runs.