Not enough heat!

[jcappe]

I'm really confused on my setup. I have a WoodMaster 4400. Forced air furnace with a water to air HX. My OWB runs at the setting of 170 off 160 on. I heat my domestic hot water as well. Here is my problem. The copper pipe going into the HX (inlet) is 160 degrees but the air temp coming out of my closest register will not go over 100 degrees. I've used two different types of thermometers. My HX is in the cold air side of the furnace. The air temp of the cold air is 61, on the opposite side (after it's gone through the HX) it is 106. My DH plate exchanger is transferring heat as well. Last year I was getting close to 130 degree air temp out of my registers. I'm totally lost on this. I've stuck a thermo in the water tank of the OWB thinking maybe the OWB wasnt reading the water temp right and it reads the same as the readout. Any ideas what to check next I'm about to pull my hair out???

 

[mga]

from what i've read around here...shouldn't the temp be like 185 degrees?

 

[jcappe]

I think most Central Boilers run hotter than the WoodMaster. Woodmaster factory setting are 170 off 160 on.

 

[Slick]

What jumped out at me in that description was last year you got 130degree out of exchanger,this year 106....that tells me the exchanger isn't exchanging as much as last year....either build up inside the exchanger (lime etc) or buildup outside the exchanger (dust etc). you said it's in your cold air return, you do have a filter before it right?

 

[jcappe]

Filter is right before the HX. I clean it at least once a month. I also took the duct work apart to look at HX. It's as clean as the day it was put in. I'm thinking the HX has to have build up in it. I don't understand why when there is no draw on the system the inlet and outlet pipes are the same temp. Here are a couple of pics of my setup. First one shows where hx is in duct work on the cold air side.

 

[Slick]

By no draw on the system you mean no fan blowing through the exchanger? I've never checked my temp with no fan on but I doubt it would be much of a temp drop...if absolutely nothing then maybe you do have some buildup, could be insulating the exchanger from the inside?

 

[jcappe]

By no draw on the system you mean no fan blowing through the exchanger? I've never checked my temp with no fan on but I doubt it would be much of a temp drop...if absolutely nothing then maybe you do have some buildup, could be insulating the exchanger from the inside?

Correct, no draw meaning the furnace fan is off. I keep telling my dealer that with my hard water I'm thinking it is build up but he says he has never seen one build up. I'm religious about using the corrosion solution at each fill up so I'm not sure what to think. I was thinking of maybe trying a new pump just to see if maybe it's circulating enough to keep the lines up to temp with no draw. Once the system starts drawing heat off of it, things really go to hell. My domestic hot water is only 120 degrees now. I'm not sure what it use to be but I know it takes more to get the water to a comfortable temp this year than it did last year in the shower. Also turning a tub or even a water faucet to hot will bring down the temp enough on the aquatstat to kick on my backup lp furnace. The copper line going out of the hot water heater went from 160 to 105 when I tested earlier today.

 

[ericjeeper]

sounds to me like your circulating pump is slowing down.Your delta Tee is way off on that domestic heat x

 

[Slick]

Wouldn't the delta go up if the pump was slowing down? Wait...maybe your talking the delta of the air..I was thinking delta of the water....

 

[jcappe]

sounds to me like your circulating pump is slowing down.Your delta Tee is way off on that domestic heat x

We just tested the old pump. The old pump took just over a minute to fill a 5 gallon bucket WoodMaster said it should fill it in 30 seconds. Put the new pump on and had almost the exact same scenario. So now we are thinking it is in the DHW plate exchanger or the HX in the furnace. We are going to bypass the DHW exchanger first and see if that changes things.

 

[ericjeeper]

Wouldn't the delta go up if the pump was slowing down? Wait...maybe your talking the delta of the air..I was thinking delta of the water....

slow flow = high delta t. 55° is a really high delta t

 

[odps]

Air in the lines?

Check for air in your lines ... do you have a valve in your system to bleed any air out?... I didn't see one in the pics...

 

[hardy steve]

I have the same results.Water temp at hx is 170.I'm not sure what the temp is coming out,but All my registers read 104 deg.House stays 74 75 nice.I'm not sure if this is good are bad,but I'm happy with it.

 

[Slick]

slow flow = high delta t. 55° is a really high delta t

Yes and he has a lower delta this year than last year...so wouldn't that mean his flow is higher than last year?

 

[boyland]

flow flow flow.... If you have the fill connected directly to your lines use th pressure from your water the purge the heat exchanger. I notice after mine sits they always work better if I high pressure force water through them.

So I use my water pressure to flush out the exchangers.

Just a thought.

 

[mtfallsmikey]

flow flow flow.... If you have the fill connected directly to your lines use th pressure from your water the purge the heat exchanger. I notice after mine sits they always work better if I high pressure force water through them.

So I use my water pressure to flush out the exchangers.

Just a thought.

IMO, need a Y-strainer in the supply inlet(s) on both DHW/OWB to the HX...

 

[jcappe]

My dealer was out there today. No restrictions in the DHW plate exchanger or the heat exchanger? I have no idea what is going on. For the guys that are using and OWB, what is your water temp at and what are you getting for heat out of your register vents?

I have 160 foot total of pex...do I need to add another Taco?

 

[applefarmer]

150 ft from boiler to furnace, 1" pex in house, logstor in ground. Set point on boiler is 135 on 165 off. Temperature out of registers is 135-140 according to ir thermometer. One pump on back of boiler.

It sure sounds like a flow issue. You said the original pump was only putting out half the volume it was suppose to, did you check the performance of the new one?

 

[ericjeeper]

What size taco pump

oo7?Or an 09? 013?

 

[jcappe]

Put new pump on and had the same flow rate. Just over a minute to fill a 5 gal bucket. I'm using a Taco 011