Radiant Heat GPM problem

tyronesheat

First hello to all and thanks in advance for reading this post. I am having an issue with my radiant heat and I am hoping that I can get a little help. My radiant heat consist of 4-4 loop Uponor Stainless manifolds with flow meters. I am using .5in Wirsbo pex staple up with 8 in spacing and 2 loops in each bay. I have Uponor joist Trak and I literally used in on the entire staple up system. I am using 4 Grudnfos s26 99 3speed circulators with 4 watts 160 temp valves. (this is my secondary loop) . My primary loop has Taco 007. I also have a Weil Mclain Ultra 105 boiler with a pressure release valve and spiro vent. Lastly all my loops are between 225 and 260ft. On each manifold I am within 10% of the other runs.
So let me try to set this up for you. My house has 2 floors, each floor I have 2-4loop manifolds hence 2 up and 2 down is 4 manifolds. I have a primary 007 feeding a loop that breaks off into the 2 manifolds, each manifold has a Grundfos circulator with a temp valve. All 1inch copper and when the loop feeds into the circulators steps down to 3/4inh.
The problem I have having is I only have .6gpm on one of the four loops. The other loops range from .3-.4 and sometimes im getting .15-.2. Even with the speed turned up all the way on the circulators I still cant seem to get .6gpm.
Now this all happens with the temp valves wide open so I am letting the least amount of cool water return to the manifold BUT if I adjust the temp valve to lets say half way I can get the gpm to increase. This is killing me. We also shut down the the first manifold on the loop so all the water goes to the second manifold and the gpm jump in the flow valves but the gpm will stay up. Forgot to mention I had Taco 007 first and I only saw .3 and .15 gpm.
Remember I said one manifold is working great. Flow is perfect and I can adjust with no problem at the flow meters. The other 3 manifolds are wide open and Im only getting .4avg. HELP because I am out of answers. I am sure I left a few things out so please ask me questions. If I need pictures I can load them up. I will probably load them up anyway just to see it. Thanks.

aircooled81

.6 gpm? I couldnt find a pump curve for s26-99, but ups26-99 do like 0 gpm at 24.5 to 29 ft of head. Do radiant zones have that much pressure drop?
Can you meassure the entering and leaving temp drop, then compare between the 'good zone' and the bad zones? The higher the difference, the lower the flow.
If its air, that could impeded flow, are the 2nd floor zones giving you the most problem? Where air is more likely to hang out.
Could not figure out in my mind how closing a zone down increased gpm?
Air can join your sytem through make upmwater, but it can also be sucked back in through an auto airvent if the suction/return pressure at that point was lower than atmosphere, and expansion and compression tanks can put air into a closed system by leaks or bad airtrol fitting.

Other things that lower gpm, restriction like wye strainer, closed valve, impellar issue, but i think unless this has accumulated over time, air sounds like a more reasonable explenation why more than one pumped zone appears to be flowing less to you.

Gordy

What type of mixing valve are you using? And is the circ pulling through the valve, or pushing? Is this all a single temp system? Or do different zones require different SWT?

If the system requires same SWT through out you do not need the mixing valves for the radiant with that boiler?

I suspect the mixing valve as the issue. Wrong type of cv rating, and it's maxed out on temp.

SWEI

How long are your loops?

Zman

Gordy said:

What type of mixing valve are you using? And is the circ pulling through the valve, or pushing? Is this all a single temp system? Or do different zones require different SWT?

If the system requires same SWT through out you do not need the mixing valves for the radiant with that boiler?

I suspect the mixing valve as the issue. Wrong type of cv rating, and it's maxed out on temp.

I agree that the mixing valve is the likely culprit. It could also be a piping error.
Why are you mixing a condensing boiler?
Do you have pictures?

tyronesheat

I have thermostats on all the manifolds. They are on the supply and return. The delta varies from 20-40 degrees on the loops that read .3-.4 gpm. On the good loop the delta is less than 20 and even 10 most of the time. It;s not really a matter of 2nd floor vs 1st floor. Each floor has 2 manifolds and the first manifold on both floor are better than the second manifolds on the loop. I had to take apart the Spiro vent because the float was stuck so maybe its still not right? I can hear air in the pipes and i do see a few bubbles here and there. I am using Watts160 mix temp valves. The temperature is about 130 going in although I did test it out and got it up to 155 just to see if I could read that on the manifold. The temp valves are before the circulators so its pulling from them. THE CRAZY THING IS IF YOU OPEN UP THE TEMP VALVES TO LET MORE RETURN WATER BACK IN THEN THE FLOW GOES UP TO .9GPM. IF YOU SHUT DOWN THE TEMP VALVE SO LESS RETURN WATER GOES IN THEN GPM GOES DOWN TO .4. ARRRRRRGH..... I also have baseboard heat that will be hooked up to this system as well as my DHW. My plumber whom is really good is also stumped by this and the reason for the temp valves is to prevent too high of a temperature going to the floor. I read that the mixing valves are a must with a radiant heat system?

tyronesheat

Here is a pic of one of my units. I have 4 like this. Watts mixtemp160, Grundfos s26 99 3spd uponor manifold with flow meters. Poor gpm, open up the mix temp valve gpm increases, close it and gpm decreses. Can use this to adjust flow because it will not allow enough hot water into the system (max temp using this way is 110)

tyronesheat

My goal, I should be able to adjust the flow from 0 to 1.5 on speed one. I do have one manifold that I can do this with and it works perfect. The other 3 are wide open and the gpm is low.

tyronesheat

null
loops are between 225-260. Keep in mind that I have 4-4loop manifolds and on each 4 loop manifold the lengths are within 10% of each other.

tyronesheat

Below are some pictures as it is set up today. You can see the panoram of all 4 manifolds. The picture of the one manifold, circulator, and mixing valve show the whole set up.

tyronesheat

This picture shows one full set up with few markings. HELP ME....SOMEBODY. Im thinking the mixtemp valves are a factor. My plumber also said maybe the screens are getting clogged up a little bit. Air, clogged screens......

Gordy

That's a watts LF 1170? For domestic hot water mixing. Wrong type of mix valve. That's the issue. Much more resistance to flow.

Gordy

Is that an L1170 mixer? If so max mix temp is 120*

SWEI

Four mixing valves and four UPS 26-99 pumps? Yikes.

Don't just change the valves, fix the design. It may not cost any more (and just possibly less.) Who's buying?

Gordy

Do all mixed zones require different temps?

Zman

The mixing valves are certainly restricting your flow. It is hard to tell from the pictures how the boiler is piped.

It is true that you should not send extremely hot water to the infloor loops. It is also true that high efficiency boilers are not highly efficient when the return water temp is high.

Your system should have been designed so that all the zones need approx the same water temp. The boiler water temp should be controlled using outdoor reset and mixing valves should not be there at all.

The circulators alone are wasting hundreds of dollars a year in electricity.

The workmanship looks great. The design has issues.

bmwpowere36m3

Those are some serious pumps for 1/2" PEX in 260' loops... Besides low flow rates, is there an actual issue? As in, insufficient heat?

Gordy

Flow is the issue. Due to mixing valve. High deltas.

tyronesheat

As usual one guy that knows nothing but has lots to say....SWEI. Appreciate your jokes but trying to fix a problem here and the other fellas seem to have good input so please troll another post or go play candy crush or something.

Fellas, the mix valve is a Watts 1170 series but its the M2. Yes the 1170 is 120max temp but the 1170m2 is 160max. All zones are set to the same temperature. The only reason why I was playing with the mix valve is to see if anything happens to the flow. The system was thought out very much. There are a million ways to do it but the way this is set up is there is a Primary pump from the boiler, for each primary pump there are 2 secondary pumps. The Grundfos are the secondary pumps and the primary are Taco 007. From the boiler there is a small loop (1inch leaves the boiler through the 007, goes to 2 Grundfos which pump the water throughout the 2 manifolds. My house is 2700sqft, even with this issue and only insulation, no sheetrock yet the house was at 70 degrees downstairs and 65 upstairs with outside temperature at 4 degrees. This was this past weekend. I lowered it to 57 downstairs and 54 upstairs because I am not in the house and guess what. Today the water froze in two lines because it doesn't run enough. Its not a matter of not working but I am trying to fine tune the system.

tyronesheat

You guys are correct in that I think the problem is at the mix temp valves. I learned last night and today that there is way too much restriction with the mix temp valve closed down meaning i need to let more water back into the system on the return side and balance out the flow meters. Doing this the gpm is better but I couldn't balance the system. Does it makes sense to you guys that the mix temp valve closed down increases the restrictions. FYI the mix temp valve alone is 6ft of head loss. I am up around 25 at the max distance of 265ft. Grundfos 3speed allows me to set it depending on which manifold I am on. Never the less the temperature is the same for all manifolds. I am running preprogram and custom boiler reset programs and the boiler is heating up the water based on the temperature outside.

STEVEusaPA

...As usual one guy that knows nothing but has lots to say....SWEI. Appreciate your jokes but trying to fix a problem here and the other fellas seem to have good input so please troll another post or go play candy crush or something...

Well being rude to one of the most experienced, knowledgable and well-respected people on the forum won't win you any points.

tyronesheat

One more detail, the boiler was inactive for 9 months. We hooked it up and ran it. Maybe rust and other elemenst are clogging the mix temp valves. Having the boiler serviced this week.

Gordy

The boiler can not introduce rust into the system. However there may be plenty of other debris in the system from installation that may have fouled the mixing valves screens.

Read the valves manual they need minimum 30 psi to function properly.

Gordy

Personally you should listen to SWEI. His recommendations will save you in operating costs, system simplicity, and component reduction.

tyronesheat

Yeah im thinking that too Gordy. Also the spirovent may not be 100%. The fact that the one is working so good really means some fine tuning. Those mixing valves the more I play with them make a huge difference. When I open them up and let as much possible return water back into the system gpm goes up.

Gordy

That's because by design it takes very little hot water to mix with warm return to make set temp. The hot has more restriction.

tyronesheat

I am looking up right now how temper valves work. I mean i know what they do but how do they work.... New news but starting to make sense.

SWEI

No snark intended there. Allow me to elaborate a bit:

The mixing valves are indeed the problem. The 26-99s were a band-aid to try and make those work. If you replace all four thermostatic mixing valves with more appropriate models, you will have four massively oversized pumps and you will still have a system that produces less comfort at a lower efficiency than it should.

As others have suggested, start with a heat loss calc and then compare that with the emitter capacities. Hopefully they will be able to run on one water temp. If so, you can install zone valves on each manifold and feed them using a single ECM variable speed circ. Result? No more mixing valves and an 80% (or better) reduction in pumping power consumption. If it turns out you need two different supply temps, the Ultra can manage that sequentially. If the mismatch is severe, you might have to add one more motorized ODR-controlled mixing valve and a second pump.

tyronesheat

STEVEusaPA said:

...As usual one guy that knows nothing but has lots to say....SWEI. Appreciate your jokes but trying to fix a problem here and the other fellas seem to have good input so please troll another post or go play candy crush or something...

Well being rude to one of the most experienced, knowledgable and well-respected people on the forum won't win you any points.

Well I am looking for help and the system is allready put together, obivously it works but just beating me up about the design and no suggestions is cool but its all good.
I posted so I'll just take the good and the bad.

tyronesheat

Zman said:

The mixing valves are certainly restricting your flow. It is hard to tell from the pictures how the boiler is piped.

It is true that you should not send extremely hot water to the infloor loops. It is also true that high efficiency boilers are not highly efficient when the return water temp is high.

Your system should have been designed so that all the zones need approx the same water temp. The boiler water temp should be controlled using outdoor reset and mixing valves should not be there at all.

The circulators alone are wasting hundreds of dollars a year in electricity.

The workmanship looks great. The design has issues.

Apologies, just frustrated trying to fix problem. Do you have any suggestions on the current system other than changing what I have right now. The boiler is piped with 4 zones. 2 zones are radiant heat, 2 zones are baseboard. I also have hooked up to the boiler a Weil Mclain indirect water heater. The 2 radiant zones each have a primary Taco 007 and each of the primary circulators lead to 2 Grundfos circulators. So in all I have 2 Taco and 4 Grundfos for my radiant heat. Each of the 4 Grundfos circulators have the Watts 1170M2 160max temp valves. The return water comes down do a T and it goes to the mix valve or back into the system. Oh yeah im letting the boiler do its thing. Has preset selections for radiant, basebord, custom, a few more but im on custom right now. Water is going into the manifolds about 120-140. It was just a test i did real quick to see if i could get 160 out of it and i can but I wont do it because it will definitely screw up the hardwood floors.

tyronesheat

SWEI said:

Four mixing valves and four UPS 26-99 pumps? Yikes.

Don't just change the valves, fix the design. It may not cost any more (and just possibly less.) Who's buying?

Im buying.
Do you have any thoughts on the mix valves all he way open s being all the way closed?

hot_rod

One quick and simple thing to try is remove the guts from the mix valves. Oddly enough they will still do some temperature blending, but you will eliminate that huge pressure drop. They "become" a manual 3 way mixer like the early days of radiant.

It was common fix on some of the early prefabbed control panels from one radiant manufacturer when they switched brands and didn't look at the Cv of the replacement valve

Gordy

tyronesheat said:

Zman said:

The mixing valves are certainly restricting your flow. It is hard to tell from the pictures how the boiler is piped.

It is true that you should not send extremely hot water to the infloor loops. It is also true that high efficiency boilers are not highly efficient when the return water temp is high.

Your system should have been designed so that all the zones need approx the same water temp. The boiler water temp should be controlled using outdoor reset and mixing valves should not be there at all.

The circulators alone are wasting hundreds of dollars a year in electricity.

The workmanship looks great. The design has issues.

Apologies, just frustrated trying to fix problem. Do you have any suggestions on the current system other than changing what I have right now. The boiler is piped with 4 zones. 2 zones are radiant heat, 2 zones are baseboard. I also have hooked up to the boiler a Weil Mclain indirect water heater. The 2 radiant zones each have a primary Taco 007 and each of the primary circulators lead to 2 Grundfos circulators. So in all I have 2 Taco and 4 Grundfos for my radiant heat. Each of the 4 Grundfos circulators have the Watts 1170M2 160max temp valves. The return water comes down do a T and it goes to the mix valve or back into the system. Oh yeah im letting the boiler do its thing. Has preset selections for radiant, basebord, custom, a few more but im on custom right now. Water is going into the manifolds about 120-140. It was just a test i did real quick to see if i could get 160 out of it and i can but I wont do it because it will definitely screw up the hardwood floors.

I know you pinged zman, but I'm a bit perplexed about your p/s piping because it sure does not sound like it.

In a true p/s piped system there should be a primary loop with one circ, and a pair of closely spaced t's for each secondary zone with ether a zone valve, or a circulator driving that zone.

tyronesheat

hot rod said:

One quick and simple thing to try is remove the guts from the mix valves. Oddly enough they will still do some temperature blending, but you will eliminate that huge pressure drop. They "become" a manual 3 way mixer like the early days of radiant.

It was common fix on some of the early prefabbed control panels from one radiant manufacturer when they switched brands and didn't look at the Cv of the replacement valve

Really, wow. Seems to be a lot with these mix valves.

tyronesheat

bmwpowere36m3 said:

Those are some serious pumps for 1/2" PEX in 260' loops... Besides low flow rates, is there an actual issue? As in, insufficient heat?

Heat is fine, House heats up and stays warm but I have all new insulation. So this was a ranch, I gutted it and went up. I wish I did 2x6 but I wasn't up to par on all that and I did 2x4 but needless to say I have r15 in the walls and r38 in the ceilings. I also spray foamed all the windows, doors, big cracks, and caulked the small cracks. Heat is good even with the low flow.

hot_rod

tyronesheat said:

hot rod said:

One quick and simple thing to try is remove the guts from the mix valves. Oddly enough they will still do some temperature blending, but you will eliminate that huge pressure drop. They "become" a manual 3 way mixer like the early days of radiant.

It was common fix on some of the early prefabbed control panels from one radiant manufacturer when they switched brands and didn't look at the Cv of the replacement valve

Really, wow. Seems to be a lot with these mix valves.

Watts does promote that valve as a radiant mixer, here is the pressure drop curve.

It does show the valve with check valves and filter screens option. If it has those, remove both. In a clean, closed loop system no need for those fine mesh screens and they may well be plugged, from startup.
Same for the checks, they are intended for domestic water systems where there is the potential for pressure differences between H&C.

Now it is possible the installer removed them, but it is an easy first step.

bmwpowere36m3

I don't want to take away from what anyone has said… but if heat is fine in the house, then take a breath. Members such as SWEI, Gordy, Hot Rod, Zman are all VERY knowledgable. I would listen to them.

Think long-term… which is what they are getting at. Having 4 mixing valves and 4 huge circulators is really a waste. Especially the circulators, think electrical cost $$.

Whether you need 1 GPM per loop depends on heat loss. Have you performed a room by room calculation? You say each floor has 2x 4-loop manifolds… at 1GPM and 10* delta (per loop) that's ~ 40k BTU's for each floor (piping is capable of carrying). Does that sound about right? Installation, water temp, delta and GPM will actually determine the BTU output.

The easiest and cheapest thing to try is what Hot Rod said, remove the guts of the mixing valve and see if that bumps up your flows… just keep track of actual floor temps, especially if you have hardwood.

tyronesheat

Gordy said:

tyronesheat said:

Zman said:

The mixing valves are certainly restricting your flow. It is hard to tell from the pictures how the boiler is piped.

It is true that you should not send extremely hot water to the infloor loops. It is also true that high efficiency boilers are not highly efficient when the return water temp is high.

Your system should have been designed so that all the zones need approx the same water temp. The boiler water temp should be controlled using outdoor reset and mixing valves should not be there at all.

The circulators alone are wasting hundreds of dollars a year in electricity.

The workmanship looks great. The design has issues.

Apologies, just frustrated trying to fix problem. Do you have any suggestions on the current system other than changing what I have right now. The boiler is piped with 4 zones. 2 zones are radiant heat, 2 zones are baseboard. I also have hooked up to the boiler a Weil Mclain indirect water heater. The 2 radiant zones each have a primary Taco 007 and each of the primary circulators lead to 2 Grundfos circulators. So in all I have 2 Taco and 4 Grundfos for my radiant heat. Each of the 4 Grundfos circulators have the Watts 1170M2 160max temp valves. The return water comes down do a T and it goes to the mix valve or back into the system. Oh yeah im letting the boiler do its thing. Has preset selections for radiant, basebord, custom, a few more but im on custom right now. Water is going into the manifolds about 120-140. It was just a test i did real quick to see if i could get 160 out of it and i can but I wont do it because it will definitely screw up the hardwood floors.

I know you pinged zman, but I'm a bit perplexed about your p/s piping because it sure does not sound like it.

In a true p/s piped system there should be a primary loop with one circ, and a pair of closely spaced t's for each secondary zone with ether a zone valve, or a circulator driving that zone.

Yeah thats how it is. Does this help

Gordy

Uhmmm no. Not seeing p/s. Need pics of boiler piping.

tyronesheat

bmwpowere36m3 said:

I don't want to take away from what anyone has said… but if heat is fine in the house, then take a breath. Members such as SWEI, Gordy, Hot Rod, Zman are all VERY knowledgable. I would listen to them.

Think long-term… which is what they are getting at. Having 4 mixing valves and 4 huge circulators is really a waste. Especially the circulators, think electrical cost $$.

Whether you need 1 GPM per loop depends on heat loss. Have you performed a room by room calculation? You say each floor has 2x 4-loop manifolds… at 1GPM and 10* delta (per loop) that's ~ 40k BTU's for each floor (piping is capable of carrying). Does that sound about right? Installation, water temp, delta and GPM will actually determine the BTU output.

The easiest and cheapest thing to try is what Hot Rod said, remove the guts of the mixing valve and see if that bumps up your flows… just keep track of actual floor temps, especially if you have hardwood.

Yeah mybadd to all members. I'm new and all ears. Thanks for all your help guys. Long term, I see. The issue I have is that low gpm with these beast pumps all but one manifold which is amazing with the flow and delta.

Gordy