It's cold. Poor Unico install. Want to re-use 3rd fl. radiators

ivanator2

We bought a large 1888 victorian in Minneapolis last Spring. It had freeze damage, so all the radiators on the first and second floor had cracked or burst. The third floor radiators survived.



We accepted a bid and had a Unico heating and cooling solution installed in April. A 3.5 ton air handler, cooling module and heating coil. We also had a new 120K BTU boiler put in.



The heating module is not able to heat the house. It's currently in the low 40's downstairs and upper 50's upstairs. And it's going to be getting colder. My wife is 9 months pregnant with the baby due in two weeks, and we also have 3 and 1.5 yr. old girls at home. Contractor has so far not been very responsive. The guy who installed the boiler has been out. But that was 16 days ago. I don't get responses for days, and now I've been told some guy is out of town and they'll be in touch. At this point, I have to start considering solutions on my own.



I want to bring down the third floor radiators and use them on the first floor. I believe I'll need to create a second zone. I would be setting up six radiators. Is there anywhere to go to read up on this? I've worked with black pipe gas lines, and I replaced all the burst copper supply lines with new copper running up to a second floor pex manifold, running pex from there to bathroom fixtures.



We need to get moving on something now. Any and all advice welcome.

Gordan

Need more information

What kind of boiler? Does it fire? What is the supply water temperature? What is the return water temperature? What's the air temperature at the outlet of the hot water coil? How was the cooling performance of the Unico system this past Summer? Did the Unico contractor install the hot water coil, or did the boiler guy? What are the specs on the coil? On the blower?



You can bring down those radiators and hook them up for the expense of a couple hundred bucks, but that doesn't guarantee that they'll be able to heat the space adequately. Best to figure out what exactly is the issue with the current system.

ivanator2

Unico/radiator combo

It's a Slant Fin 150K BTU 84% eff boiler. It works. The boiler guy came out and raised the temp 30 degrees. He works for the same company - they did all the work. He said he raised it as high as it would go. The cooling worked really well. No load calc was done.



If the thermostat is never satisfied, would the Unico unit run constantly? I would think it would run constantly, but it seems to shutdown, like the thermostat is satisfied, but the temps are only in the upper 50's.



The specs:



LENNOX 22W85 3.5 TON R410 SERIAL#

MC3642BL1-EC1 COIL

MB3642L BLOWER

MH3660 HEATING COIL



It's heating and cooling a leaky 3500 sq ft(approx) house. The third floor is finished as well, but we chose not to condition that space. That's where we'd get the radiators - those did not burst. We are doing our best to tighten it up. The house has 22 windows downstairs. Of those, 8 are newer, double-pane. The house has a large 32 ft x 16 foot central foyer with an open central staircase. The thermostat is at the top of those stairs. There simply is not enough warm air rising up that staircase to reach room temperature, which is surprising to me.



Here's what I think, but HVAC is not a strength of mine. The unit sits on the second floor. They ran a plenum in a couple different directions. But 40% of the outlets for the first floor are longer runs, from 20 to 35 feet. The outlets for the first floor are in the ceiling. There is very little air velocity at those outlets with the long runs. There are only two outlets per room - doesn't matter how big the room is. These rooms are 16x16 and 16x12. So two outlets with low volume is not going to generate much heat and it's not going to aspirate the air either. But that is probably fine for cooling. Not heating though.



They stubbed in a copper tee with a shut-off valve for the supply and return off the boiler, because I was going to have them come back and run pex to the radiators on the third floor.



I would like to run pex off that tee to a pex manifold, then off to each of the six radiators. Can I do that and have it all be one zone, or do I have to make a second zone for the radiators? I might hire someone. I might try and tackle it myself.

Gordan

Need more more info

Again, you need to measure the supply and return temperatures for both air and water. You can do that with a cheapo digital meat probe and it will be better than knowing nothing. We need to narrow down what the problem is. You could have flow problems on the water side. The boiler could be undersized. The distribution on the air side could be inadequate.



If the boiler is undersized, connecting it to different emitters is not likely to help.



If the boiler is adequate and the problem is with the coil, yes, you could run a separate zone for the radiators. You definitely do not want this on the same zone. Get a separate circulator for this zone and pipe this in parallel with the Unico zone. Make sure that there are check valves installed (some circulators can accept them right in the outlet, or install separate ones) to prevent backflow. Home-running the radiators to a pex manifold will probably be the easiest way to get something that works well enough.

Mike Kusiak_2

Cast iron radiators

Are the radiators on the third floor the large old style column type with a high water content? They might be the case if the house originally had a gravity hot water system as implied by its age. They typically operate at much lower temperatures than the heating coil in the air handler so you may not be able to just parallel them with the heating coil. Even if on its own zone, without some sort of mixing valve arrangement the boiler would not be able to supply the two different temperatures of water necessary.



Another possibility would be to run inexpensive fin tube baseboard on the first floor which would be more compatible with the water temperature requirements of the heating coil. You could then leave the cast iron on the third floor and attend to the complexities of properly connecting them later.

Jim Pompetti

Fan control

is the temperture of the fan control . It ia always a bad idea to replace hydronic with hot air

ivanator2

Radiators

I've attached a picture of what one of the radiators looks like. The boiler we replaced had a pump on it. It was a Weil McLain boiler.



I also did a BTU calculation on the radiators for the first floor and it came to 75,000 BTU's.



The new boiler is a Slant Fin 150K BTU boiler. I wonder if it would have enough BTU's to suppy the Unico System hot water coil, as well as the radiators on the first floor, assuming we replace with similar radiators.

AFred

Panels?

You might want to look into panel radiators.

My back hurts thinking about hauling those rads down 2 floors.

If you are looking for a contractor, I work in your neighborhood, and I can recommend 1 or 2 other contractors too.

I am dying to know who did the install.

-Andrew

NewtoHeatHelp

Keep Us Posted...

Keep the wall posted with what you end up doing. We bought a house with freeze damage, cracked radiators, but new boiler so I'd like to salvage that. Right now using the electric furnace to (expensively) put some type of heat (not enough) into our old house that sounds very similar to yours. I'm really interested to hear what you end up doing.

ivanator2

water flow rate.

So I've been going through the documentation trying to figure out the capacity of the heating coil. It depends on the water flow rate. How would I determine what the water flow rate would be? Is that a reading on the boiler?



Also, I've found some air leaks in the ductwork. One of the two plenums is all puffed out. There's actually a slit or cut in the side and when I push in on it, warm air comes out. There are also some warm air leaks right around the takeoffs near the air handler. The tape for the take off joints isn't even adhering to the joints in a few locations and I feel warm air coming out. Should all this be absolutely air tight?

Robert_25

lots of things going on here...

That is a big house with a lot of windows...and it sure sounds like something is not up to the task. I think forced air is a terrible idea for a house like yours, but it sounds like you need to work with what you have.



Does the boiler cycle on and off the high limit? If it does, boiler capacity isn't the problem. My first thought is that the water temperature drops in the air handler's coil and the blower shuts off to avoid blowing cold air. What are you using for a circulator on the air handler zone? It should be located right near the boiler.



The other thing that isn't helping is blowing the heat down from the ceiling. Your home probably has 9 or 10' ceilings? Did the contractors install cold air returns on the first floor?



Baby due in two weeks...I sure hope you can get it fixed by then.

John Mills_5

Help is here

Seems to me if you found a Wallie that serves your area, check into his services. 

ivanator2

Update

After speaking to various folks, including people at Unico corporate headquarters, I've concluded a Unico heating module, even the biggest one with the biggest Unico blower, will not heat a 3500 sq. ft. house as a single zone. There needs to be one Unico system per floor.



My system averages 875 CFM. At most, if there are no inefficiencies in the system, it will put out 70,000 BTU's.



Adding more outlets would increase the CFM by approximately 200 CFM, but that still would not be enough for a single zone.



So my options are add a second Unico zone for heating the first floor only along with  additional outlets, or add a second zone of radiators.



The contractor who did the install did the following wrong:



- Did not design the layout to permit for any balancing between Summer and Winter. The layout is essentially optimized for cooling the house.

- Did not configure the system correctly, so we weren't even running in what's called "High Heat" mode, which is a configuration switch. This pumps out more CFM.

- They're initial response to the issue was to turn up the water temp at the boiler to 220 degrees, which made things worse. The blower would heat up too much, so it would shut down. The system was behaving as if it were cycling down. Max water temp for a Unico hot water coil is 180 degrees.

- Did not install enough outlets to maximize the CFM the system is capable of.

- And most of all, did not understand the system would not heat the house without an additional Unico zone.

Robert_25

So what are you going to do?

I would do a heat loss calculation on the first floor and install the required radiation as a second zone. You may be able to repurpose those cast iron radiators, but if they haven't been pressure tested...you might move a lot of iron for nothing. Fin/tube baseboard is relatively cheap, and there are high-ouput versions available if you have some high-heatloss rooms with minimal wallspace.

walnuts

things you've probably checked

3500 sq. ft seems huge for a 3.5 ton ac system.     but that being said I thought I read that the ac worked fine for the conditioned space.    carefully check the supply and return piping to the coil when the system is running for heat.  Is the return almost as hot as the supply?    I know it sounds crazy but when did the air filter get changed last?   generally with the packaged unico air handler it is easier to meet the heat load than it is the cooling load assuming adequate boiler size, as long as the piping to the coil is properly sized and connected to the right pump.  Not positive but I think unico recommends at least 8 supplies per ton that would mean a minimum of 28 supplies for 3.5 tons cooling.

ivanator2

Adding Radiators to a Unico System hot water coil - silt?

I haven't had much luck finding folks in town to help me. It seems folks don't want to get involved in a botched HVAC install, and critiques of the boiler and Unico install also vary widely.



We've decided to add radiators to the first floor. I also have what may end up being an undersized boiler - a Slant Fin Sentinel SE-140. The old boiler was a 200K boiler



The Unico System is clearly not cut out for heating this house. The maximum BTU output of one Unico hot water coil is a theoretical 90K btu. But Unico support says a more realistic expectation is 70k to 80k btu. And I have 3500 sq. feet  to heat.



I was wondering if there was silt in old radiatorsand if they were added to the current Unico System hotwater coil, would the silt end up circulating through the Unico hot water coil? I have some old radiators I'd like to reuse



I can't find anyone knowledgeable enough about he Unico hotwater coil in Minneapolis to help me - I've concluded folks take a class or two and there is no technical depth. It all starts with the manufacturer in my opinion.

Robert_25

Measure twice, cut once...

Have the radiators you want to install been pressure tested? If not, I suggest you take the time to do it. It isn't much fun to move those big chunks of cast iron around only to find out they leak rusty water all over the floor when pressurized.



Next question, have you done the math to see if the radiators you have are sufficient to heat the first floor?

ivanator2

Radiators will be sufficient

The old radiators put out about 70,000 btu's for the first floor, if my EDR calcs were correct.



At this point, I'm going to begin to gradually add radiators to the first floor. I only have 50,000 btu's available to me for first floor radiators, because the Unico hotwater coil is using about 70,000.



I would eventually throttle back the btu consumption of the Unico hotwater coil, concentrating it's btu's on the second floor, so I should be able to get closer to 70,000 btu's of radiators on the first floor.



I have a large foyer with a central staircase open to the second floor, so I probably need 60 or 70 percent of the btu's concentrated on the first floor.

Mike Kusiak_2

System and piping design

Have you thought about how you are going to connect the new cast iron radiation to the boiler? The air handler coil and the cast iron radiation will probably require different water temperatures. If you just connect the two zones together in parallel, when the cast iron zone calls for heat, the high mass and water content will quickly cool down the boiler to a temperature insufficient for the coil.



An idea might be to use an electronically controlled mixing valve to provide the proper temperature water for the cast iron radiation. Some of the posters here have recommended the Taco electronic mixing valves which provide outdoor reset control of the water temperature, so the radiators only heat to the temperature required under current weather conditions.



http://www.taco-hvac.com/uploads/FileLibrary/100-19.pdf



Seems like something worth looking into.

Paul48

Spring

I'd set it up temporarily to give priority to the first floor.A call for heat by the 1st floor stat opens a relay and shuts off the 2nd floor.This makes the full output available to either floor, just not at the same time. Sort it out in the spring.

Alan_13

perhaps get existing system tuned in first

"If the thermostat is never satisfied, would the Unico unit run constantly? I would think it would run constantly, but it seems to shutdown, like the thermostat is satisfied, but the temps are only in the upper 50's."

just my two cents, but how about getting the unico to run constantly first before changing rads around,  maybe it will give enough heat and give you time to sort things out

ivanator2

couple things

The maximum water temperature of the Unico System hot water coil is 180 degrees. This is the last system with some fancy blower, and it has a lower maximum temperature. The maximum temperature of hot water radiators, I believe, is 180 degrees. So there would not need to be any mixing. I currently have the boiler temp set at 180.



When the contractor who did the original install came out the first time to troubleshoot, he turned up the boiler temp to 220 degrees. That resulted in the Unico blower shutting down every 5-10 minutes because it was getting too hot.



The contractor also installed ball valves off the boiler, so he could later come back and add pex lines to radiators. But I believe they're only 1/2 inch, so not sure if that will throttle the flow to any radiators.



The circulator pump is also on the return side.

Paul48

?

Let me guess...........he plumbed to the heat exchanger in the air handler with 1/2" pex?