Heating/pump issues

colbyd49

Hey everyone, I have a new house and recently turned on the floor heat and I feel like there is issues. I have a 1,900 SF home, 2 zones ran about 700LF in each zone however it’s ran as one zone with one pump grundfos 15-58fc. Closed loop hot water tank. Pump was installed to suck and not push so it’s installed at the end of the loop so now the issues.

Mechanical thermostat is set at 70 and hot water tank is set at very hot. The furnace thermostat will read 70 sometimes but the tile never feels warm. Sometimes I feel like the system struggles and never gets to 70 it will linger around 68. I woke up at 3am this morning to a very loud noise. It was the pump just screaming and was very hot. I shut everything down and turned the furnace on.

I live in Oklahoma and we’ve had a mild winter so I feel like the system shouldn’t be struggling. Any thoughts are appreciated

Thank you

Jamie Hall

I'm afraid we need a lot more detail... this is, I presume, radiant floors? with 700 feet of pipe in each zone?

Starting there. The heat source. You mention a hot water tank. As in -- conventional hot water heater, as might be used for your domestic hot water? Not the ideal heat source for radiant floors, but it can be made to work Sometimes. Is it gas? Oil, Electric? What is it rated at, in BTUh or watts?

How does this compare with the heat loss of the building?

Are those 700 foot zones in one single loop, or are they divided into multiple parallel loops? If they are parallel loops, how long are they? And what size is the pipe? What is the pipe spacing in the floor?

Is there a expansion tank on the system? How big is it? Where is it located relative to the pump? What pressure is it set at?

I hope there is at least one pressure gauge on the system. What does it read with the system cold? With the system hot and running?

colbyd49

You’ll have to forgive my ignorance. I’m new to this setup so I may ask dumb questions. Yes radiant floors. 700lf in each zone approximately. Together it’s 1,400lf approximately. Yes traditional hot water tank. Rheem is the brand. It’s a stand alone unit and doesn’t have anything to do with my other hot water tank. My mimicked my brother in laws setup and his works great and he has a bigger house. It’s gas. I’ll have to look at BTU when I get home from work this evening.

Not sure what you mean by heat loss of the building. My house is pretty well insulated from heat loss if that’s what you are asking. I can turn the fireplace on and it’ll heat up the entire house within a few hours and hold heat for most of the night.

2 zones but ran as one. One zone is 700lf and the next is 700lf. It essentially splits the house in half. 1/2” pipe pex pipe with o2 barrier. About 1’ apart. Ran parallel some runs might be 20-30’

No expansion tank and unless there’s a pressure gauge on hot water tank itself which I don’t believe I’ve seen than that’s a no as well.

System is ran as this. Hot water feeds from top of tank. As one line. T’s off into 2 inlets, runs thru slab, comes out 2 outlets, T’s off into one line, fed into grundsfos pump then back into hot water tank.

I’m concerned about the pump. It was very hot when I touched it this morning when it was very loud.


Thanks

Jamie Hall

Oh. Well... 700 feet of half inch pipe is a lot of head loss, even at relatively small flows. But there are a lot of other things which are, shall we say, less than ideal here.

Certainly with that much head loss in the piping you almost have to be arranged so that the pump draws from the hot water heater and pushes the water into the pipe, rather than trying to suck it out. Second, you really need to have an expansion tank on the system, piped into the system between the water heater and the pump. If you don't, sooner or later you are going to have major problems, unless you are very fortunate and the pressure relief valve on the water heater pops first. You should also have a pressure gauge on there to see what's happening.

As a wild guess, I imagine that what has happened is that the pressure has dropped in your system -- a small leak, or the pressure relief valve opening just a bit -- and that has dropped the pressure at the inlet to the pump low enough so that the poor thing was starved of water -- and that has ruined the seals on the pump, which accounts for both the heat and screech.

This sounds like a bit of a home-brew design, frankly, and there is a lot about it which isn't best practice. Sorry about that.

colbyd49

I attached a picture of a expansion tank. Does this suffice? With the head loss you speak of am I needing a bigger pump and where should I put a pressure gauge be located?

There was always some heat to the pump but during the screeching it was really bad. Is it safe to say after I modify the system and start the pump up as long as there’s no screeching it should be fine?

Jamie Hall

I doubt that the pump will be fine. The screeching almost certainly indicates that the seals are damaged, if not destroyed, and if it doesn't leak when you start it up it soon will.

The expansion tank is like what you need, but quite possibly the wrong size. Amtrol has a handy dandy calculator on their web site which will help you with sizing it.

The pressure gauge should go near the expansion tank, along with the air eliminator and a few other things -- like the pressure reducing valve and backflow preventer for connection to your water supply.

GroundUp

Can you please provide a picture of the system? First of all, a 1900 sq ft slab should have a minimum of 1900 LF of tubing in loops with a maximum length of 300ft each. If your loops are in fact 700ft long, flow rate will be next to nothing regardless of circulator size and the heat output will likely suffer forever. Perhaps the start of the loop may have a warmer floor surface while the end will be cooler. Some photos would really help clarify things, but at a bare minimum you'll need to move the pump to the supply side and verify that there is pressure in the system for it to work. An expansion tank is not 100% necessary for operation, but 110% necessary from a safety standpoint as is the relief valve.

hot_rod

Here are some numbers if in fact you have 1/2 loops 700 feet long 1' on center

At .65 gpm flow you have about 14' of head to overcome with the circulator

At 12" OC 700 feet, expect around 8 BTU/ sq ft output.

Look at a 1 gpm flow which could get you around 15 but/ hr per square foot, cost you 28' of head.

The fix I have used is to install a high head circuit and a flow reverser. It switches flow direction every 15 minuets or so to try and catch up on the load from both ends of then loop.

First determine what the heat load is, then try and figure a way to get there with what you have. The 12" oc will hurt a bit for output also.

slant fin.com has a free load calculator.

colbyd49

I turned the pump on and it sounds like debris of some sort in the propeller. Could be the seal? I’ll call grundfos tomorrow and see if I can get in warrantied. I bought it 6 months ago but turned it on after the house was built about 2 weeks ago. I brought in a different plumber and he seemed to have an idea of how to properly setup the system. He was pointing out the same issues you were Jamie.

I should of measured what was leftover on the pex pipe but didn’t feel it was necessary...until now haha. Pump will be switched around and will now push instead of suck. Plus a expansion tank will be installed with a few other things. I did attach some pics of what it looks like currently. BTUH Is 38,000.

Thanks for that info Hot Rod I will look into that! I would of never figured that out.

hot_rod

Looks like 1/2 pex feeding to the 700' loops? How long is that run?

Also that washer hose connection on the circulator is not a good idea, even more pressure drop.

Not a lot of positives in these pics, sorry

pecmsg

New House?

Who designed and installed this "System"

colbyd49

It’s two zones that act as one zone. 700lf in each zone. Yes the plumber I had look at the system said that connection is restricting the flow and he’s going to fix that

I copied the system from my brother in law in the house he built years ago. His system has had no issues but the guy who installed his had some knowledge in how the system worked. I used a different builder and this was his first time as well as myself so I can’t fault him in any way. I’m on Oklahoma these systems aren’t very common here.

hot_rod

I live in Missouri, traveled to OK on occasion. There are a few pros around and a fair amount of radiant around Tulsa I know.

Boone and Boone is the B&G rep I know down there and they design and move some well designed radiant and hydronics.`

If needed I could ask them for a couple of hydronic say guys, where are you located in OK?

Those long loops and wide spacing are going to limit your system performance, you can help some with creative retro-fits for that hydronic constipation if it does not work to your liking now.


https://www.pmmag.com/articles/87331-the-long-way-around-br-john-siegenthaler-pe

pecmsg

colbyd49 said:

It’s two zones that act as one zone. 700lf in each zone. Yes the plumber I had look at the system said that connection is restricting the flow and he’s going to fix that



I copied the system from my brother in law in the house he built years ago. His system has had no issues but the guy who installed his had some knowledge in how the system worked. I used a different builder and this was his first time as well as myself so I can’t fault him in any way. I’m on Oklahoma these systems aren’t very common here.

Why cant you fault him?

You paid for a "Professional"! Part of being a professional is to know ahead of time what will and wont work as well as accepting responsibility when it doesn't.
Another part of being a "Professional" is making every attempt to correct the unforeseen issues that do arise.

DZoro

So much painfully wrong, for starters, find a plumber who knows something. This is pretty basic plumbing and your guy doesn't have a clue how a water heater works. You are pulling out the cold inlet (bottom) of the water heater and pushing into the bottom. So you don't even have a chance to see any heat from the water heater. Pipe the supply (to the system) out the hot side/left of the water heater. While redoing that please add a pressure tank and pressure/ temp gauge. install a 30lb pressure relief.
And yes to all the above comments.
D