New installation issue

Poolman21

Hi everyone,

I'm new here so I appreciate any help you can offer. I recently purchased 1960s home with radiant baseboard heaters and an old Weil-McLain boiler. The original system just had 1 thermostat and all the heaters were connected together in a loop. I removed the old boiler and installed the new boiler in the pictures below with a Taco SR502 2 Zone switching relay so I could have separate thermostats for the upstairs and basement. The problem I am having is that everytime the lower pump kicks on (still plumbed into the original baseboard heaters in basement), I am getting heat upstairs as well. The upstairs is staple up pex tubing that I ran between the floor joists. There is a thermometer just after the upstairs pump and the temperature rises when only the lower pump is calling for heat. I'm not sure what my options are to prevent that. My best guess is that the boiler itself has has an internal pump so I'm guessing when it turns on it is pumping too much water for the pipe to handle and is sending the excess water up the tee and to the top pump. But that's just a guess. Let me know what you think. Thank you!

EzzyT

1st things first that boiler is plumbed incorrectly it needs to be plumbed in a primary/secondary piping schematic. Plus those pumps don’t have internal check valves which would prevent the ghost flow. I would start by repiping it according to the manufacturers specifications of piping schematic and install flow control valves for each one of those pumps.

Ironman

There's no internal pump on that boiler.

Like Ezzy said, pipe it p/s and install flow checks.

Poolman21

Thanks for the input guys. I tried to plumb in based on the drawing from the book attached below. Also, the pumps do say "internal flow check" on the side. Is there another product I should purchase in addition to that? I didn't really think it was a back flow issue since the water is flowing in the proper direction of the piping (albeit when I don't want it to) so I'm not sure a flow check would help that situation.

mattmia2

As long as they maintain the minimum flow in each loop separately, it doesn't absolutely have to be primary/secondary, does it? Er. I see the mixing valve. It would be hard to make sure that happens with the mixing valve.

Ironman

Let's see the inside of the Taco SR 5... panel.

Poolman21

I put the mixing valve in because I still have the original 3/4" thick hard wood floors upstairs and I read that water temperature shouldn't exceed 140 for wood floors. Since the boiler puts out 180 for the basement baseboard radiators I a needed a way to reduce the water temperature upstairs.

Poolman21

The left wire goes to T/T on my boiler and the other two go to the two thermostats which in return turn the pumps on when calling for heat.

mattmia2

A flow check is spring loaded, it takes a certain amount of pressure to cause internal flow through it so it stops convective forward flow as well as reverse flow. In your case depending on the resistance of the boiler vs the resistance of the other loop it may pull some flow through the other loop even with the flow check. The primary/secondary piping would isolate the 2 heating loops so that wouldn't happen.

hot_rod

The manual should show piping options for a two temperature system. Either primary secondary or a hydraulic separator.

HVACNUT

> @hot_rod said:
> The manual should show piping options for a two temperature system. Either primary secondary or a hydraulic separator.


The page is there in the photo but it's cut off.

Is the radiant circ an IFC? Can't tell in the pic. The circ for the basement zone looks like an older 007 F5.

With the diagram you followed, the inputs for space heat and the indirect are being seen by the boiler independently. No switching relay.
With your setup, the boiler only sees one input.
You might be able to make wiring, rather than piping changes.

I'm not familiar with your boiler but it obviously accepts 2 inputs, minimum. You could probably eliminate the SR502, bring both circuits into the boiler and program for 2 different SWT.

What's the model number of the boiler. I'll download the I&O manual and take a peek. As if my phone's not heavy enough already.

BillyO

where do you live that the boiler can be vented with pvc?

EBEBRATT-Ed

@BillyO

Still doing PVC in MA. if the mfg allows it

Poolman21

> @HVACNUT said:
> > @hot_rod said:
> > The manual should show piping options for a two temperature system. Either primary secondary or a hydraulic separator.
>
>
> The page is there in the photo but it's cut off.
>
> Is the radiant circ an IFC? Can't tell in the pic. The circ for the basement zone looks like an older 007 F5.
>
> With the diagram you followed, the inputs for space heat and the indirect are being seen by the boiler independently. No switching relay.
> With your setup, the boiler only sees one input.
> You might be able to make wiring, rather than piping changes.
>
> I'm not familiar with your boiler but it obviously accepts 2 inputs, minimum. You could probably eliminate the SR502, bring both circuits into the boiler and program for 2 different SWT.
>
> What's the model number of the boiler. I'll download the I&O manual and take a peek. As if my phone's not heavy enough already.
>


Thanks for being so helpful. The boiler is an HTP UFT-140W.

You are right, the circ for the basement pump is recycled from the old boiler. I did however put a spring check valve where it comes back up out of the concrete on the far left.

Poolman21

> @BillyO said:
> where do you live that the boiler can be vented with pvc?

Pennsylvania

fenkel

Install ifc at pumps...check to make sure your three way value isnt backflowing hot water back into the upper zone...
I would check to make sure your 3 way valve is installed correctly.
Could it be flipped over?...is the hot coming into cold and cold coming into hot sides on it? Cant tell from picture...
Also pull out valve and see if anything could be lodged in it.
Is it a new 3way valve?
What happens if you where to shut off the return valve off on the manifold on the right?


The htp uft boiler will work fine without p/s header.

HVACNUT

You can go into settings and use CH for the radiant and the DHW input for the high temp basement zone.
You can control SWT and min/max firing rate for each input individually.

Poolman21

> @fenkel said:
> Install ifc at pumps...check to make sure your three way value isnt backflowing hot water back into the upper zone...
> I would check to make sure your 3 way valve is installed correctly.
> Could it be flipped over?...is the hot coming into cold and cold coming into hot sides on it? Cant tell from picture...
> Also pull out valve and see if anything could be lodged in it.
> Is it a new 3way valve?
> What happens if you where to shut off the return valve off on the manifold on the right?
>
>
> The htp uft boiler will work fine without p/s header.



Everything is good on the 3 way mixing valve. It's new, working properly, and plumbed correctly.

I don't think flow checks will help because it's not back flowing. I know this because I feel the temperature of the copper and I can tell that the water is flowing in the proper direction based on which pipe is hotter, supply or return.

Im starting to believe the pump is just too powerful. It seems to me that the water cannot all flow through just one pipe so excess pressure is forcing the water down the other pipe as well. I'm not having any short cycling issues that I can tell. I've never gotten an error code and the boiler doesn't seem to cycle on and off. I'm guessing a p/s loop would give the extra pressure a place to escape but I don't want to do that and find out it didn't help unless someone is fairly certain that it would.

Thanks for the response.

Poolman21

> @HVACNUT said:
> You can go into settings and use CH for the radiant and the DHW input for the high temp basement zone.
> You can control SWT and min/max firing rate for each input individually.

I am using the DHW for the hot water to the house so I don't think that would work.

mattmia2

A flow check also prevents forward flow unless there is enough pressure to overcome the force of the spring. It prevents reverse flow and prevents forward flow with the pump off.

Poolman21

> @mattmia2 said:
> A flow check also prevents forward flow unless there is enough pressure to overcome the force of the spring. It prevents reverse flow and prevents forward flow with the pump off.

I suppose a flow check is cheaper, faster, and easier than a full P/S loop or a hydraulic seperator so it's probably a good place to start. I suppose I could also use motorized valves which would be wired into the same relay as the pump, so they only opened when the pump was on. Think that would work as well?

HVACNUT

> @Poolman21 said:
>
> I am using the DHW for the hot water to the house so I don't think that would work.


I didn't see an indirect in the pic. Sorry.
Then the P/S piping arrangement should have been used.

You at least need an IFC or flow check for the upper zone. There shouldn't be migration on the basement zone.

mattmia2

I would go with the p/s before the zone valves. There are 120v zone valves that would wire right in to the pump control, ideally with the boiler opening the valve then the end switch on the valve controlling the pump, but it is far better to do it primary/secondary, that way you are guaranteed to keep the minimum flow through the boiler regardless of how much the mixing valve is pulling from the boiler vs from the return of the loop.

There are IFCs for most pump models that just push in to the outlet of the pump so it is just the $20 or whatever for the IFC, unbolt the flanges and pop it in, although I don't recommend this unless you are sure it will keep the minimum flow through the boiler for all conditions of boiler temp and mixing valve state.

BillyO

there's no way that manual has a schematic that resembles pic. That boiler has an internal pump. It needs to be piped p/s. What is there isn't even close. You can try all you want , its never going to work as it should

mattmia2

That boiler does not have an internal pump unless it is something other than a UFT-??0

BillyO

The UFT has an internal CH Primary Pump

BillyO

OMG, a disagree!!!

lchmb

http://www.htproducts.com/literature/lp-542.pdf actually the UFT does not show an internal pump. However I would suggest repiping it primary/secondary as shown on page 24. It will respond quicker and have less short cycling with the radiant loop..imho..

fenkel

Just finished install a 80 uft floor version today, no internal pump..
Most will agree to use p/s header..

BillyO

if that uft in the picture is a combi it has an internal CH Primary pump. The UFT heating only doesn't have internal pump. Look at pic again

HVACNUT

> @BillyO said:
> OMG, a disagree!!!

No internal pump equipped with that boiler.
Multiple piping option diagrams in the manual.
P/S piping requires a field supplied boiler primary circulator.

Agree the OP should repipe in P/S for that particular setup.

mattmia2

Is this actually a UFTC, not a UFT?

hot_rod

A red and blue Pex going to it

lchmb

yup.. Billyo is correct.. missed the hw pipe.. but I'd still pipe it primary/secondary.."shrug"

Poolman21

It is a combo unit

Here is a close up picture of the outlet and inlet. If I just tee these two together would that make a p/s loop? Can I just put the branches facing each other and connect or do I need to put the branches pointing up towards the boiler and bring my inlet and outlet water into the ends?

mattmia2

The place where a particular secondary loop's supply and return Ts off of the primary loop need to be within a couple pipe diameters of each other to achieve hydraulic separation of the loops (so the primary pump doesn't affect the secondary pump.)(some of my earlier advice was for a boiler without an internal pump, I didn't realize it was the combi model, the heat only model looks identical unless you scrutinize the connections to it)

The air scoop and the expansion tank should be located so the pump is pumping out of it, so the lowest pressure is at the air scoop and encouraging the air to come out of solution at that point and so it is not forcing water in to the tank instead of out through the loop. Ideally this would also be where the hottest water is but the pressure is the more important factor.

Take a look at a few of these:
https://www.caleffi.com/usa/en-us/technical-magazine

hot_rod

Determining where YOU should establish the PONPC is a bit more complicated with high pressure drop type of boilers, as many mod cons are. Multiple pump systems make it more complicated to assure all are pumping away.

Those high pressure drop boilers all want you to pump into the boiler, on the return side. Combis have that built in. That additional ∆P added helps keep that heat exchanger happy and healthy

The very best air removal is at the hottest point in the system, right at the boiler ideally. Back in the day of large chamber, cast boilers that small auto vent screwed into the boiler did a lot of the air removal function, high temperature, low flow velocity.

Keeping in mind that some, hopefully many hydronics run low SWT, possibly 120F or lower, so you no longer have that hight boiler temperature to aid air removal. I'd suggest you run all boilers up to 180F for a period to drive out all the micro bubbles and dissolved O2 and nitrogen, up to 4% in some cases, present in the fill water.

Here are a few examples of where the expansion tank location PONPC and air eliminator are split up to best leverage all the boiler and air removal requirements.

I feel most important is moving to high performance air purgers. The old scoop type just cannot provide the level of micro bubble and dissolved gas removal crucial to high performance, low mass, thin metal boilers we now deal with.
Include high efficiency air and gas removal with high efficiency boilers.

Poolman21

hot_rod said:

Determining where YOU should establish the PONPC is a bit more complicated with high pressure drop type of boilers, as many mod cons are. Multiple pump systems make it more complicated to assure all are pumping away.

Those high pressure drop boilers all want you to pump into the boiler, on the return side. Combis have that built in. That additional ∆P added helps keep that heat exchanger happy and healthy

The very best air removal is at the hottest point in the system, right at the boiler ideally. Back in the day of large chamber, cast boilers that small auto vent screwed into the boiler did a lot of the air removal function, high temperature, low flow velocity.

Keeping in mind that some, hopefully many hydronics run low SWT, possibly 120F or lower, so you no longer have that hight boiler temperature to aid air removal. I'd suggest you run all boilers up to 180F for a period to drive out all the micro bubbles and dissolved O2 and nitrogen, up to 4% in some cases, present in the fill water.

Here are a few examples of where the expansion tank location PONPC and air eliminator are split up to best leverage all the boiler and air removal requirements.

I feel most important is moving to high performance air purgers. The old scoop type just cannot provide the level of micro bubble and dissolved gas removal crucial to high performance, low mass, thin metal boilers we now deal with.
Include high efficiency air and gas removal with high efficiency boilers.

Thanks for the info. Man, so many ways to skin a cat. That's the first drawing I've seen with the expansion tank on the cold side.

mattmia2

Look at the idronics link i posted above, it is basically a hydronics textbook in .pdf form

Poolman21

Hey Guys,

Just wanted to thank everyone for the help. Off work for now so I'm going to rip this thing apart and re-plumb it. Can you take a look at the drawing below and let me know if you think it will work? Sorry for the crudeness, I'm still new to this.

Thanks again for all the help so far. Just trying to learn how to do this right from the beginning to develop good habits.

hot_rod

The pump in the boiler, it should be on the return side pumping into the boiler?

The air purger is in a good spot, I'd move the expansion tank to the return of the secondary loop, this assures all circulators are pumping away from the PONPC. Assuming the boiler circulator is pumping into the return.

That "horseshoe" loop pipe needs to be sized large enough to handle the total flow rates, one size bigger would not hurt as it does serve as part of the hydraulic separation, the expansion tank shown in the color schematic shows the expansion tank being referenced for all the circulators thru the generously sized piping.

Avoid what we call a bull head tee, bottom left of the drawing where flows come from two directions on the run and go out the branch of a tee.