Hi All I ill try to make this as short as possible but it will be hard. I built a new home 5 years ago with between the joist radian heat. my basement has radiant heat in the concrete and works perfect. the first 2 years no issues with the 1st floor(only 1 floor) staying warm in the northen Maine winter. the last 3 years it has been harder and harder for the house to maintain 70 degrees on really cold days. Jump to now. I am in the process of installing UPNOR aluminum plates as they were not previously done. I just found out that the 4th and 5th loop in the zone is warm at best. the total run for that loop is 280 feet. the tile above the floor has cold spots and now I know why. does that loop need to be bleed? any help would be great. I have 3 loops in that zone and the other 2 loops are fine. any help would be great. Out going temp from Manifold is 122 degrees temp at loop 4 is 78 degrees,

That sounds plausible. If the manifold valves are clear of obstructions and open then it could be air pockets. What is your total flow and flow per loop? If your flow per lop is toolow, it may not be able to self purge the air. If you close all the loop valves but one, and force all the flow thru that one loop, you may be able to force the air out of that loop. If it is a small circ pump though this may not be enough and you may need to use an external pump(large sump pump in a large bucket) to force high flow thru one loop at a time to purge the air...

thanks for the reply, new update. 1st I have no clue as to my flow. I am in rural Maine and the plumbers I have spoken to up hear are clueless and my checkbook cant afford them shotgunning parts. I have a Grundfos circulating pump that was set to medium. I switched it to high and it seemed to help then after an HR the inlet side temp of the pump was at 160 (set point as at 130) and the discharge side was luke warm. I woke up this morning and the discharge side of the pump is still luke warm with the inlet side the same. I will try to bleed the system today to see if that helps. this is the 2nd pump that has been installed in 3 years Thanks for anyhelp anyone might help Larry

A couple thoughts,
Is this one pump and zone valves? If so and you do need to replace the pump again have a look at the Grundfos Alpha or Taco Viridian. These both can be set to pressure differential and will increase or decrease velocity as needed.
Next is there a proper air eliminator (large brass object the primary loop passes through with vent on top or side). Without that you may never properly scrub the air out and ultimately create an air pocket in a loop or group of loops, this also can occur if you install manifolds below the floor they serve.
Last to go with the air scrubber an auto fill is needed to top off the boiler, may only be a cup of water but a cup of air in the wrong spot can cause cavitation and prevent water flow.
Dan

good morning thanks for the reply. Yes I have the items you listed in the reply. I have 1 zone with 3 separate loops and it is the longest loop that is giving me problems, the other 2 loops in the zone are perfect. I turned up the single pump to high nd that seemed to help a little.. I still believe I have a flow issue and I do not understand how to adjust my brass Uponor true flow manifold to properly balance my loops. I do not believe my plumber knows how either. I live in bum*^&$ Maine. I will try to get my plumber here to bleed the zones and see if that helps also. been 5 years and the system has never really worked as needed. everyyear I am trying something. this one loop in the zone is frustrating. thaks fore all the help

Blueridge Company
Thank you for your reply. I know it is a lot to ask but would it be ok if sent pictures of my system as that could answer a lot of questions you might have? and how do I send or attach pictures on here?

thank you for your help

I would be glad to look at a photo,
You can e mail me directly if you prefer,
[email protected]

Posted By garrett on 12 Oct 2015 08:37 AM
good morning thanks for the reply. Yes I have the items you listed in the reply. I have 1 zone with 3 separate loops and it is the longest loop that is giving me problems, the other 2 loops in the zone are perfect. I turned up the single pump to high nd that seemed to help a little.. I still believe I have a flow issue and I do not understand how to adjust my brass  true flow manifold to properly balance my loops. I do not believe my plumber knows how either. I live in bum*^&$ Maine. I will try to get my plumber here to bleed the zones and see if that helps also. been 5 years and the system has never really worked as needed. everyyear I am trying something. this one loop in the zone is frustrating. thaks fore all the help

Is that new radiant heat trend use Grundfos Alpha??? I didnt find any information except they have large display shows energy consumption and GPM.

I just got a Grundfos Alpha. It's great. Quiet, uses about 1/4 the electric power that my old one did, and it has a smart mode that I don't fully understand, but it seems to do a great job of automatically adjusting the flow in that mode.

What type of Grundfos Alpha did you exactly get? I searched for Grundfos Alpha but found many variations of this pump.

ALPHA 15-55F
ALPHA 15-55FR
ALPHA 15-55SF
ALPHA 15-55F/LC
ALPHA 15-55FR/LC
ALPHA 15-55SF/LC

please help choose better options.

thanks all for the reply. I am now convinced now after reading the posts and ding some experiments that I do have a flow issue on my first loop (the longest) I have a 3 loop Uponor brass true flow manifold. how do I adjust this thing to balance my 3 loops? Any help woul dbe great.

Larry

It is always a challenge to make an existing hydronic radiant installation that wasn’t initially properly designed to subsequently operate well and long. You might want to consider how this should have been designed (i.e., what the appropriate circuits lengths, flow rates, and temps should be given the heat loss) and then try to move the existing installation in that direction to the extent that this is still possible. You can accomplish a design using the free DIY software on our website:

Borst Hydronic Radiant Floor Heating Design Software

In this case, the design may not be proper since many of the design parameters are now fixed given this is an existing installation. However, you can still vary the design parameters that are not fixed to determine if you can obtain an acceptable design. If you have manifold(s) with balance valve(s) and temp/flow rate gauge(s), you can then adjust the balance valve(s) to obtain the design circuit flow rates and you can adjust the boiler supply temp to obtain the design circuit temps.

Do you have any idea how long the loops are?

What type radiator are you using, under subfloor, on top of subfloor, with/without aluminum plates, concrete?

Can you post pics of your pump panel/system?

Do you have an IR thermometer? One way to balance is to adjust the flow thru the loops so you get the same return temp out of each loop. Shoot a little spot of flat black spraypaint on each return line just before it enters the manifold. The flat spraypaint gives a place with a good constant emissivity for the IR to read consistently. Cover the tubes at the paint spots(and several inches either side) with insulation that can be easilly removed to shoot temps. The insulation will allow that paint spot to warm to very near the fluid temp inside the line, so try and shoot the temp quickly after lifting the insulation. Then adjust the manifold loop valves open or closed to get the same return temps when heating is called. This may not be productive if there is another problem with that loop besides being longer(kinked,clogged,air pocket).

Not necessarilly the best option if one loop is drastically longer than the others, but being already installed, it is what it is. Once the loops are temp balanced and you are putting more flow/temp into that cold loop, you may be able to boost system temp to get a little more desireable performance out of the floor.

Excellent advice, ronmar.

Also, a good starting point is to open the long one that is not doing well all the way.

Ron, you do have to be careful about using circuit return temps for balancing the flow rates. This really only has merit for the situation where the system was actually designed such that the required zone circuit return temps are nearly the same for all the circuits. Different zones often have different heat loss and associated heat gain requirements. Unless the design actually addressed this by say varying the PEX spacing in the zones (e.g., providing less/more spacing where more/less BTU/Hour-SF was required), adjusting the flow rates such that all the zone circuit temps are the same value will likely result in some or all of the zones generating more or less heat gain than is actually required/desired. Yes, ideally a system is designed such that the required supply temps of all the circuits are indeed the same value and this value is as low as possible given other building design considerations. Doing this avoids the need for mixing values (i.e, allows using a single common boiler supply/return temp for all of the circuits) and maximizes heating system efficiency. While this design approach can usually be easily accomplished for most residential designs, it isn’t clear that this was accomplished for this OP design.

Yes, fully opening up the currently cold and likely longer circuit is a good starting point. You might even have to reduce/close some or all of the other circuits depending on the amount of available head of the existing circulator(s). Again, starting out with a proper design ensures good operational performance and minimal operational setup issues.

I agree, but it is apparently past the design stage. Yes, the cold loop willl probably be wide open, and the other two loops in that zone will need to get less flow to achieve balanced temps. It is Maine, and winter is a commin, so I am sure he just wants his floor to be comfortable Balancing the temps should at least get him a little better performance out of the loops in that particular floor zone. IF that particular cold loop is drawing more heat, by balancing the temps, it will get it(and the other two loops get less). He should then be able to play with temperatures a little to get a little more desireable outcome.

The puzzeling thing is that he was happy with it's performance for the first two years... What changed to cause the current issue?

Garrett, I think you may find that if you start trying to match temperature on those three loop lines, you are going to run into difficulty because something is keeping that cold loop from flowing properly, either air or some other issue. But in trying to balance the loops, you will probably close the other two loops, which may force any air out of the problem loop and solve your issue

I am not sure he has passed the design phase yet... It sounds like he is still adding plates to his system and he may still need to properly size the circulator. So it seems he is designing as he goes. In any event, I think he should enter his heat loss and circuit parameters into the calculator and determine the required supply temps, flow rates and pump size that will produce an acceptable solution. Right now he is just flying blind. Yes, it is entirely possible he will stumble on a solution, but why not spend 10 minutes and sort out any design deficiency. He likely already spent more time typing to this post for over a week.

Yes, it is very puzzling if his system was working well the first couple of years and is not doing so now. That would lead me to think that his system has lost hydronic fluid and he has an air blockage. However, didn’t he already purge his system? Maybe I misinterpreted what he initially wrote. Another possibility is his circulator is failing and is no longer providing the head and flow rate that it did initially. What percentage of maximum head is he operating the circulator? Long circuits needing higher flow rates to generate the required heat gain can quickly use up a lot of the available head. Operating a circulator beyond about 90% of maximum head will significantly shorten circulator life. Have the more recent Winters been colder and beyond what his system can provide? Again, this is why spending some time to sort out what is required is not a bad thing even with an existing installation.

Hi All
I will try to answer all the question and give some insight as to what I have done and found out.
I house is only 5 years old, built with ICF foam block, and 8 inches closed cell spray foam over 1 inch blue board in the attic. my basement has radiant heat in the concrete and the house is 980 SQ feet (shore land zoning n lakes in Maine sucks) the upstairs ceiling is cathedral with a 6/12 pitch
year 1 all seemed ok
year 2 started not to work well, plumber re bleed system seemed better
year 3. system would not keep up so my Circulating pump was changed. still not good so a 6 foot register on its own zone was installed in my living room of course that helped the house but not the tile floor
year 4. on real cold days -15 to -20 F the house would not get above 66F so the wife used the gas stove for an hr and the house temp would go to 70 and stay that way for most of the day.
year 5, HERE WE ARE
Yes the winters the last 3 years have been colder for longer continuus days. But with a highly insulated house it should not have been a problem.
I am not designing, I am trying to fix what my plumber is unable to do.
I work over seas so I was ever around when stuff was done but now I am home.

System before 2 weeks ago.
1. loop 1 on the manifold was set 3/4 full open. loop 2 and 3 were full open
2. No aluminum plates installed
3. all else same as below

system Info as of NOW
1. single zone with 3 loops, loop 1-260 feet, loop 2-200 feet, loop 3 150 feet, all approximately.
2. 1/2 inch pex between joist
3. 4foot x 4 inch .050 thick aluminum panels belly to but on all the tubing with silver lined bubble wrap insulation.
4. Grundfos circulating pump UPS 15-58 FC
5. House heating BTU demand upstairs 51000-64000 (basement is always nice and warm at 70F)
6. Uponor true flow brass 3 loop manifold
7. I also have all the stuff to prevent micro bubbles in the system.
8. Inlet temp 125 degree F
9. Uponor manifold is 2 feet below the tubing. thus it is upside down. the PEX comes in from the top.

Things done that made a major improvement the last 2 weeks
1. Installed the aluminum panels
2. Adjusted the Uponor valves correctly, Loop 1-full open, loop-2 1.5 turns open, loop-3 1/2 turn open, I made small moves on loop's 2 and 3 to get return temps as close as possible.

result
1. OAT was 24F
2. inlet temp 125 F, loop 1 return temp 86, loop 2 return temp 89, loop 3 return temp 91, this is the best I can get the return temps to be close.
3. house temp set at 69 and maintained at 69
4. loop 1 still seemed cooler then the other loops ( all tile under the loops) on the floor
5. Major difference on the feet as compared to last year.

Final
1. Is my circulating pump to small?
2. what is the aprox head pressure on my system?
I would like this information to give to my clueless plumber. If my pump is to small than I need him to warranty it and install the correct one but I need numbers to back up what I am saying.
I had my plumber here last week and he saw first hand that the manifold was major out of adjustment. his helper never balanced it correctly from day 1..
I live in rural Maine and the plumbers here know how to install but now how to properly adjust. His work looks very professional but looks and function are 2 different things.

thanks for any help on helping with the calculations and pump size.

Larry

I have pics but I do not know how to post them on here

You have 3 loops and you say basement in slab radiant also. Is that basement loop one of the 3 off the manifold? If not, where does it get it's hot water? What are it's supply and return temps? How much tube is in the slab? IS that 980 SQ/FT including the basement, or in addition to the basement?

Hi
The house is 980sq feet each floor. The basement is on its own zone and 100 percent isolated from the 1st floor zone. The hot water to the basement is supplied from the boiler. I have checked the basement tubes to see if any hot water was getting to that zone while the zone is on and nothing is bleeding .
The pex in the basement length is about 1000 feet spaced between 3loops