Inside Temperature not rising above 65

[Trevdor]

Hi! I just fired up my Hardy H4 last week with the cold weather and for some reason, the temperature inside the house will not rise above 65 degrees. Everything seems to be running fine with the outdoor burner. I have the water thermostat set to 180 and it is maintaining that temperature I believe, at least the fan is only blowing off and on, not continuously. The pump is running and I can feel hot water in the pipe. The water in the system is the correct height.

Inside the house the lines coming into the heater are hot, but not scalding to the touch. Is that right? The air coming out of the vents in the house is only lukewarm however. Yesterday the house was 65 at 8:00 am and only got up to 66 after running all day.

Any ideas on things I should check? Someone mentioned that maybe there was air in the system, but I'm not really sure how to bleed off air if there is.

Thank you for your time!

 

[salecker]

Sounds like major heat loss from your underground piping

 

[Woodman1]

You are either loosing heat to the ground in your underground piping or you have air in your lines. You should not be able to hold on to pex pipe for more than a second or 2 with 180 degree water in it. I would guess air. You will have to crack open a line at a connection with the circulator running somewhere to get it out

 

[Trevdor]

I've used the burner for 5 years and haven't had this issue so I'm guessing it doesn't have to do with losing heat through the pipes since nothing has changed. Would loosening the pipe coming out of the pump work to get rid of the air? And then let the pump run for a minute?

There is a drain valve at the bottom of the Hardy, but I think that is just primarily for draining the water in the off-season.

 

[Ashful]

Inside the house the lines coming into the heater are hot, but not scalding to the touch. Is that right? The air coming out of the vents in the house is only lukewarm however. Yesterday the house was 65 at 8:00 am and only got up to 66 after running all day.

Not sure what the "heater" is, whether an air exchanger, radiator, or baseboard. But baseboards and radiators typically run 180F, which is way too hot to touch without burning. If you're able to hold a hand to it for more than a few seconds, it's likely below 120F / 49C.

I have zero experience with OWB's, so take this with a serious grain of salt, but it sounds like the line losses are greater than anticipated. I don't understand the idea of water in the lines, as I thought these systems recirculated, thereby eventually pushing any air out of said lines if properly configured.

What's the line size, insulation, pump CFM, and BTU's or watts generated?

 

[Tonty]

I've used the burner for 5 years and haven't had this issue so I'm guessing it doesn't have to do with losing heat through the pipes since nothing has changed. Would loosening the pipe coming out of the pump work to get rid of the air? And then let the pump run for a minute?

There is a drain valve at the bottom of the Hardy, but I think that is just primarily for draining the water in the off-season.

If this is the first time firing it this year, it could be line loss. Just because it was okay last year isn’t a given that everything is okay this year. Something could have impinged on your pipe insulation over the summer.
Check for air in the lines first, if that doesn’t take care of it, compare the water temp right out of the boiler with what it is going into the house.

 

[maple1]

I've used the burner for 5 years and haven't had this issue so I'm guessing it doesn't have to do with losing heat through the pipes since nothing has changed. Would loosening the pipe coming out of the pump work to get rid of the air? And then let the pump run for a minute?

There is a drain valve at the bottom of the Hardy, but I think that is just primarily for draining the water in the off-season.

That is how it can happen. Water works it's way into the lines over time and suddenly it does it enough that all your heat is going into the ground. Hard to know without accurate temp measuring though. You should try to get accurate temps on the line going to the house, as far away from the boiler as you can before it goes into the ground. Can use a dual probe bbq thermometer and tape or tie a probe against the pipe under some pipe insulation. That's a starter thing to check. Could also be an airlock or circ issue. Also you didnt say what your boiler temp is. Things just feeling hot is very hard to judge. 180 will burn. I think 120 you might be able to hold on for a few seconds.

 

[hedge wood]

Do you happen to have a Y strainer in the system that is plugging up and cutting the flow down going to your heat exchanger?

 

[Trevdor]

Mmmm... I don't think so, but I am pretty clueless about a lot of this. The inside system is a heat exchange blower. Last night I took the pump off of the outside wood burner and found a lot of dead stinkbugs up around the copper coils. I was hoping that was the culprit, but unfortunately no change. I thought this evening I would try to see if there was any air stuck in the lines by loosening the hose going from the heat exchange back to the wood burner. If that doesn't work my next guess was to try to flush the whole system, but I'm not sure exactly how to do that.

 

[Trevdor]

Yesterday I found a drain on the bottom of my wood furnace and so I drained some water out of that hoping that it might free up any trapped air. I also loosened the hose from the heat exchange, just enough so that a little water would drip out. I'm not sure if either were effective. We did get slightly warmer air temps in the house, but the weather outside has been warmer as well.

 

[salecker]

Look for any valves up high
to get rid of air you need to bleed it out of high spots

 

[Woodman1]

Look for any valves up high
to get rid of air you need to bleed it out of high spots

Yes this. And if you dont have any, go to the highest spot in your loop and cut in a t and a couple valves so you can

 

[salecker]

When i built my system i was given a tip on air removal using a pump and magic bucket.
5 gal bucket 1/2 full of your liquid a paddle pump and a couple of pieces of hose.Hook the pump to a low valve and fill into the low valve have the return come out of the top valve let the pump run making sure the bucket has fluid in it. The moving liquid will carry the air out of the top valve,pump till no signs of air coming out of the hose from the top valve.
Keep the end under the level of the fluid and you will see when the air bubbles stop.
Done,put the stuff away.Or like me leave it in place till you need to do it again.
I added a set of rads to my operating system without shutting down or introducing any air into the system. But i have lot's of valves to use.

 

[Trevdor]

Well, I've tried a few things, but I'm not having much luck. I've measured the water temperature a couple of times, is a 10 degree drop over the heat exchanger good or bad? Seems like I've read some people have more like a 30 degree drop. Maybe not enough heat is being transferred to the air for some reason?

 

[Woodman1]

I think rule of thumb is 20 degrees. Mine is 30 but I have a large hx and my circulator set on low. I purposely have the large spread to help with stratification in my storage. Generally a high flow results in a lower spread and a low flow will be a higher spread. Do you have a 3 speed circulator? I would think if it was a flow or air issue you would be seeing opposite of what you are. The longer/slower the water is in the hx the more heat will be pulled out of the water unless it is so cold there isn't much difference in the temp between the return air and the water. Really need to know the loss of water temp from the boiler to your furnace and if your pump is cavitating or not?

 

[maple1]

Try going back and reading all the replies in this thread again.

 

[Trevdor]

Ok, over the last couple of days I measured temp and tried to pressurize the system. I plugged a water hose into the drain line, turned off the pump and ran water through the whole system backwards. I could see air pockets coming up through the pipes, but that could have been from the hose. I let it run for a couple of minutes until there was no air coming through the line. I did that twice in the last two days. Maybe a slight improvement in temp, but I don't think so. I guess there could still be air in the high points of the line though.

I also measured the temperature of the water inside and out. I'm only getting a degree or two drop in temp from the outside to the inside, and about a 10-12 degree drop over the heat exchange.

I'm not sure what cavitating in the pump is. Is there a way I can check that? Could there be something wrong with the heat exchange itself?

 

[Woodman1]

Sure sounds like you got the air out of the system.

Cavitation is basically a fancy term for sucking air. Usually the pump makes all kinds of gurgling noises when this is happening.

How long has your system been installed? Has it ever been tested with extended cold temperatures like we are having now and did it work correctly?

If you are not loosing temperature in your underground lines and your hardy is correctly coming up to set point it is either a pump issue or a hx issue. Possibly scaled up inside the hx? Do you use water treatment chemicals in your boiler? I have no idea how to clean a hx. I assume remove it and flush with a weak acid solution. Maybe someone with experience doing that will chime in

 

[Trevdor]

Yeah, no gurgling sound in the pump. We've lived in the house 5 years and I'm guessing it was around for at least that before, although I'm not sure. We've used it in extended cold temperatures before, but seems like there is always something that goes wrong at least one time during the winter. Don't use any kind of chemicals in the boiler.

 

[maple1]

Ok, over the last couple of days I measured temp and tried to pressurize the system. I plugged a water hose into the drain line, turned off the pump and ran water through the whole system backwards. I could see air pockets coming up through the pipes, but that could have been from the hose. I let it run for a couple of minutes until there was no air coming through the line. I did that twice in the last two days. Maybe a slight improvement in temp, but I don't think so. I guess there could still be air in the high points of the line though.

I also measured the temperature of the water inside and out. I'm only getting a degree or two drop in temp from the outside to the inside, and about a 10-12 degree drop over the heat exchange.

I'm not sure what cavitating in the pump is. Is there a way I can check that? Could there be something wrong with the heat exchange itself?

I'm a little unclear on your flushing. You mentioned connecting a hose to a drain. Then pumping the water backwards. Usually drains are in a low spot, and pumping it backwards means pumping in one direction, so there would still be piping you didn't run water through. Water should be run in both directions from the connecting point. Since a drain is in a low spot, and an air bubble could be in any high spot anywhere.

 

[Trevdor]

Yeah, the drain is in a low spot, so I guess there could still be air in a high spot. Although I did see quite a bit of air coming through the line. The way the Hardy system is setup is the drain is connected to where the return water from the house comes back into the heater. There is also a valve to close that line before it goes back into the heater, so I closed that and connected the hose. So the hose is forcing water the opposite way it normally flows. It goes back through the return line, through the heat exchange, through what is normally the hot water line, back through the pump, and back into the tank. So I could see the air coming up back into the pump and then hear it gurgling out into the tank. Hope that makes sense!