Heating problem - I don't understand HVAC

[ericjeeper]

yep you need a faster pump.Currently ot is moving through the HX to slow and is dumping to much heat.

 

[urhstry]

OK, I am going to try a 007 since I have a new one on hand, if that makes a difference I am going to go ahead and get a 011.

Now, how is the 30 plate for my application. Still an issue or can't we tell yet?

My return lines are hot....

 

[November Wolf]

DId you happen to put a wye in the line to the heat exchanger? Maybe it needs to be cleaned out?

 

[urhstry]

Yes, there is a wye at the HX and I just checked them a few days ago when all this started.

Something I might be forgetting to tell is that I have the water circulating through the oil burner with a 007 pump from the HX to the burner (right next to it). And as mentioned, the 009 feeds the HX from the OWB. Just amking sure that what is being said here is to replace the 009 pump at the OWB with a 7 or 11. Thanks everyone!

 

[outbackrider]

A 009 Taco should work from the owb to the HX. How well is your house insultated? When you say the unit can't keep up with the heat demand, when it is bitter cold, seems it could be lack of insulation in the house.

Your exchanger could be larger, set it on 2" foam board and wrap it in fiberglass insulation.

Are the 2 pipes running from the heat exchanger to the oil furnace hot the full length? Run your hand over the full length of both pipes, if they are hot where you can't touch them and then drop to warm then you have an air lock. I mean they should be really hot the full length of the pipe. An air lock can occur in the exchanger or near the pump. I had this problem this year, I had to bleed the air out of the boiler by cracking the Taco flange and adding water to my oil furnace, bled the air, then my house got warm....nice....

I had air in both my exchanger and pump on my oil furnace side, I couldn't figure it out. The pipe from the exchanger has a 007 pump and was boiling hot, but when I ran my hand down to where the pipe enters the oil furnace it was only warm and I just couldn't get the oil furnace water up in temperature...I finally figured it out, I had air. Hope it's a simple fix....

Keep working on it...eventually you'll figure it out.

 

[urhstry]

A 009 Taco should work from the owb to the HX. How well is your house insultated? When you say the unit can't keep up with the heat demand, when it is bitter cold, seems it could be lack of insulation in the house.

House is insulated but drafty and out inthe middle of nowhere and at the full mrecy to the weather and wind.


Your exchanger could be larger, set it on 2" foam board and wrap it in fiberglass insulation.
Are the 2 pipes running from the heat exchanger to the oil furnace hot the full length? Run your hand over the full length of both pipes, if they are hot where you can't touch them and then drop to warm then you have an air lock. I mean they should be really hot the full length of the pipe. An air lock can occur in the exchanger or near the pump. I had this problem this year, I had to bleed the air out of the boiler by cracking the Taco flange and adding water to my oil furnace, bled the air, then my house got warm....nice....

Pipes are very hot.... can't touch them.

I had air in both my exchanger and pump on my oil furnace side, I couldn't figure it out. The pipe from the exchanger has a 007 pump and was boiling hot, but when I ran my hand down to where the pipe enters the oil furnace it was only warm and I just couldn't get the oil furnace water up in temperature...I finally figured it out, I had air. Hope it's a simple fix....

Keep working on it...eventually you'll figure it out.

Or Spring will come

 

[outbackrider]

Right, once March comes, the weather will get warmer.

Just double check the pipes from the exchanger to the furnace, be absolutely certain that they are hot the full length.

What is the water temperature reading on your oil furnace?

 

[KsWoodsMan]

Yes, there is a wye at the HX and I just checked them a few days ago when all this started.

Something I might be forgetting to tell is that I have the water circulating through the oil burner with a 007 pump from the HX to the burner (right next to it). And as mentioned, the 009 feeds the HX from the OWB. Just amking sure that what is being said here is to replace the 009 pump at the OWB with a 7 or 11. Thanks everyone!

That makes sense. With a 20 GPM pump, the oilburner is able to remove the heat from the water in it's system much faster than the OWB can replenish it with an 8 GPM pump. They at least need to be equally sized with the supply having any advantage available.

Yes , if you have a spare 007 and you can wire it in easily, that should get you up to temperature in the house

 

[urhstry]

Thanks KS.. I am going to try that first thing in the morning.

 

[Blazin]

Went thru the same thing with the hookup to my mom's house from my OWB. As already stated you want a pump with more volume, plate exchangers need that to work efficiently from what I've found...I'm running a 11 on a 120ft run to the house thru a 50 plate and it's doin the job nicely. Setting the high limit on the OWB to 195 makes a big difference too.

Good luck gettin that heat crankin!

 

[urhstry]

Well after a few attempts at changing pumps and insulating other small items, I am having the same problem. I had an OWB install guy stop by and he told me everything looks good as far as my setup. Which leaves the HX as my problem source. I guess i am going to buy a 50 plate and see what happens. I just don't want to spend money I already do not have. Anybody have any other suggestions? Thanks

 

[November Wolf]

If you buy a heat exchanger go check ebay. I bought my 40 plate exchanger on there and the price was cheaper than my local dealer.

 

[urhstry]

yep, that's where I got my 30 plate. I just want someone to tell me that I am doing the right thing and that I should go with the 50 as compared to the 40 or the 60.

 

[November Wolf]

yep, that's where I got my 30 plate. I just want someone to tell me that I am doing the right thing and that I should go with the 50 as compared to the 40 or the 60.

This is where I bought mine.http://cgi.ebay.com/OUTDOOR-WOOD-FU...emQQptZLH_DefaultDomain_0?hash=item2304b1e241

And here is some info I copied from that site.

HOW TO BUY A BRAZED PLATE HEAT EXCHANGER

1. The most important thing is the length and width of the heat exchanger. Ours are 12 inches. This is important as it has the most heat transfer area. It's not how many plates the exchanger has that is important but first as stated above the size!!!!!!

2. The port size is important. Most furnaces use 1 inch tubing so make sure you are not buying 3/4 inch ports as this will decrease water flow to the rest of your system. Ours are 1 inch.

3. Make sure you properly size your heat exchanger. Here is a guide based on 12 inches

A. 10 plates are used for domestic hot water or small infloor heat areas less than 1100 sq ft. will work with the largest of domestic hot water systems and should never need to be larger that this unless you will be using domestic hot water for more that 3 hours straight at one time.

B. 20 plates are used for smaller homes from 1000-2500 sq ft

C. 40 plates are used for larger homes from 2500-4500 sq ft

D. 70 plates are used for areas 5000-7000 sq ft areas.

The above is a guide to help you. If there is any question always buy the next size larger just to make sure. All items above are based again on 12 inch with 1 inch ports

4. Make sure you have a good warranty and make sure that the person you buy from sells only heating products as the others may not be there to service you down the road.

 

[KsWoodsMan]

ok, here is what I found out. When my upstairs and downstairs calls for heat, I get a drop across the heat exchanger of 45 degrees or more...so that is the temp of water going through my house and that is why I am not getting heat. I am only circulating 140-150 degrees of water and my house won't catch up.
Now how do I solve this?

The water temp coming of the OWB stays close to the set point of 195 and recovers pretty quick after a load. So doesn't that say the pump is doing an ok job or are you still suggesting that I get a 007 or 011?

I have bled these pipes about 50 times, there is not much more I can do for that.

Are you still losing 45° in the oil burner when both zones call for heat ?
you may have a restriction in the HX, OWB supply or return causing the low flow . even with the larger pump installed.

Is the water temp of the OWB still recovering as quickly?
If you are getting the the full flow and pulling more BTU's from it , then it should take longer to recover.

Are you pulling the the hot water from the top or bottom of the OWB reservior ?
The water at the top of the OWB reservior should be the hottest as heat rises. Drawing the hottest water from the top will translate to more heat to the house.

And, What size lines are running from the OWB into the house ?
Most OWB owners will reccommend 3/4" or 1" lines. Larger lines are less restrictive and able to deliver more volume meaning more BTU' s to the house. A couple of OWB owners have reported satisfactory results with 5/8" line but I wouldn't suggest going smaller because of the restricion a long run would cause.

 

[John D]

Maybe Im wrong,but I think your 30 plate is doing the job if its pulling 40 degrees off the water as it heads back to the OWB...I have a 50 plate exchanger,and Im so glad I went with it...with my incoming temps at 180,if i have one zone on,I lag 6-10 degrees lower at the oil fired boiler than the incoming temps,if a second zone kicks on it can drop 10-15 degrees below,a 3rd zone,and it can drop 20 degrees sometimes.I wouldnt want to see how much it would be dropping with a smaller HX.
Another issue could be if your pex lines are not separated by at least one wrap of insulation,the outgoing cold water that passed thru the hx cools off incoming hot supply side on its way back....this problem gets worse the more you pull out of the pex,as the temo differential gets larger,this becomes more of an issue...

 

[urhstry]

Are you still losing 45° in the oil burner when both zones call for heat ?
you may have a restriction in the HX, OWB supply or return causing the low flow . even with the larger pump installed.

Yes, still a large drop. Install is new and flow is very good. I have tap -offs that I can run the water into a bucket and the flow is there.


Is the water temp of the OWB still recovering as quickly?
If you are getting the the full flow and pulling more BTU's from it , then it should take longer to recover.

Yes, OWB has no problem keeping up with demand.

Are you pulling the the hot water from the top or bottom of the OWB reservior ?
The water at the top of the OWB reservior should be the hottest as heat rises. Drawing the hottest water from the top will translate to more heat to the house.

From the top on both pumps.

And, What size lines are running from the OWB into the house ?
Most OWB owners will reccommend 3/4" or 1" lines. Larger lines are less restrictive and able to deliver more volume meaning more BTU' s to the house. A couple of OWB owners have reported satisfactory results with 5/8" line but I wouldn't suggest going smaller because of the restricion a long run would cause.

1" pex was used.

 

[urhstry]

Maybe Im wrong,but I think your 30 plate is doing the job if its pulling 40 degrees off the water as it heads back to the OWB...I have a 50 plate exchanger,and Im so glad I went with it...with my incoming temps at 180,if i have one zone on,I lag 6-10 degrees lower at the oil fired boiler than the incoming temps,if a second zone kicks on it can drop 10-15 degrees below,a 3rd zone,and it can drop 20 degrees sometimes.I wouldnt want to see how much it would be dropping with a smaller HX.
Another issue could be if your pex lines are not separated by at least one wrap of insulation,the outgoing cold water that passed thru the hx cools off incoming hot supply side on its way back....this problem gets worse the more you pull out of the pex,as the temo differential gets larger,this becomes more of an issue...

Problem is, is that if one zone calls for heat, it drops 25-40 degrees off the HX. OWB side = 200, Oil Burner side = 165....two zones, 150, 3 zones...etc
Keeping in mind I have another pump going off the OWB to a radiator/fan to heat the garage...OWB STILL can keep up. The only variable I see is the HX.

 

[John D]

Problem is, is that if one zone calls for heat, it drops 25-40 degrees off the HX. OWB side = 200, Oil Burner side = 165....two zones, 150, 3 zones...etc
Keeping in mind I have another pump going off the OWB to a radiator/fan to heat the garage...OWB STILL can keep up. The only variable I see is the HX.

what size is your pressure side HX pump for your boiler loop?Which way is the water flowing? I used the blow off and drains,put in Tee's on both and run a 3 speed grundfos on low,(60watts),and it works great.My entire loop including HX is only 16 ft,with the hx 3 ft over the top of the boiler.I used 3/4" copper for the entire loop.

 

[tibikedad]

OK, I am going to try a 007 since I have a new one on hand, if that makes a difference I am going to go ahead and get a 011.

Now, how is the 30 plate for my application. Still an issue or can't we tell yet?

My return lines are hot....

Caution ... a 007 only has 11 feet of head (and that is at 0 GPM). If you want to push 10 GPM, the head is reduced to about 8 feet. That might not be enough for the heat exchanger, given the length of your run from the OWB to the heat exchanger.

If you choose a 011, then at the same 10 GPM, you will have 20 feet of head. This should be more than enough to push water that distance.

Remember, these circulators operate on a curve. The higher the head, the lower the GPM.