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[muffin]

My CB 6048 is having difficulty keeping its water temp.  I frequently dips down to 150F which basically shuts down flow through the house since the thermostatic valve starts dumping the supply back to the return at that point.  This irritates all my thermostats and they go into auxillary heat mode.

It seems to me that it is just not able to reheat fast enough when everything kicks on, which is bound to happen.  Particularly when I get home and crank the thermostat back up from 65 to 70.  Do you all think I should increase my water temp?  It is set to 185.  I guess it can go to 195 max, or do I need to get a blower or something to force air in and crank it up faster?  I think the root of the issue is my pool heater which put a pretty good constant load on the system a lot.  155K BTUs under optimal conditions.  It is at the end of the line, so it gets what ever is left.

[Roger2561]

My CB 6048 is having difficulty keeping its water temp.  I frequently dips down to 150F which basically shuts down flow through the house since the thermostatic valve starts dumping the supply back to the return at that point.  This irritates all my thermostats and they go into auxillary heat mode.

It seems to me that it is just not able to reheat fast enough when everything kicks on, which is bound to happen.  Particularly when I get home and crank the thermostat back up from 65 to 70.  Do you all think I should increase my water temp?  It is set to 185.  I guess it can go to 195 max, or do I need to get a blower or something to force air in and crank it up faster?  I think the root of the issue is my pool heater which put a pretty good constant load on the system a lot.  155K BTUs under optimal conditions.  It is at the end of the line, so it gets what ever is left.

I guess one thing to try is increase the temp in the house one thermostat at a time. Thus, the load will be spread out over time.  Perhaps isolate the pool heater until the house comes up to temp?  Just a thought. 

I have the programmable thermostats that come on about an hour before I get home from work.  My temp in the house is set at 62 when I'm away at work and by the time I get home the house is 68 degrees, just where I like it.  If it's a bit chilly in the house, I'll simply bump it up to 70 but generally I'll wait until the furnace has had time to recover from the shock of raising the temps.  One thing I'm mulling over is have them come on at different intervals so the heat load is spread out instead of shocking the OWB into trying to heat the house all at once.  This will allow the furnace to recover a bit before the other stats kick in to raise the temps. 

Good luck with this.  Let us know how you make out.

Roger 

[willieG]

your pool is a large draw. i think roger may be on to something with isolating your pool or perhaps even cutting the btu's delivered to the pool..spread them out more..less btu for a longer period of time? you might be able to use a valve or smaller heat exchanger on the pool so you drop the btu delivery from that huge 155K to a smaller amount but for a longer time..this may allow the fire in your boiler to also run longer but be able to keep the temp above the 150 mark? im not sure how all this stuff works but it seems to me that you should be able to instead of a huge btu shot to raise the pool  a few degrees you could adjust the flow of btus and just run that amount longer to get to the desired temp?

[johnybcold]

You might want to insulate some of the pipes inside and some boiler pipes to get more heat where it belongs what is the temp on your return?

[RSI]

I would set it up so the pool heater is disabled when the water temperature is 5 or 10 degrees lower than the on set point of the boiler. (use another strap on aquastat)
If you can turn your pool pump on and off that would be the easiest way.

But, I would make the pool heat exchanger on it's own secondary loop with it's own pump. You could also use a 3 way zone valve but they restrict flow on the entire system.

[muffin]

The people that make the pool exchanger say my pump is way undersized which explains the very long heat cycle.  They are recommending Grundfos UPS26-99FC which will move a ton more water then my current Taco 009.  This seems like it would make this situation worse; but maybe not since the returning water should be warmer.  Any thoughts?

[fireboss]

I have a taco 007 on my pool 25' away and it heats my pool no problem!

[RSI]

If the boiler can't keep up then a bigger pump will make it worse. It will make the pool heater pull it down even faster.

You need to bypass the pool heater and only use it when the boiler isn't loaded down.

Have you tried a draft blower? It used to be a $100 option and should give you a faster recovery time.


The only other option is a bigger boiler. 

[muffin]

I was thinking about a draft blower.  Do they help a lot?  The 6048 is rated to 500K BTUs so I do not understand why it is having trouble.

[Ridgekid]

Ok dumb question. How much wood are you putting in it? ( I don't think that has been asked yet)

[RSI]

I was thinking about a draft blower.  Do they help a lot?  The 6048 is rated to 500K BTUs so I do not understand why it is having trouble.

I am not really sure on a CB. I have heard that people that put them on didn't really care for them but I don't think they were having your problem. They must work though or I would think CB would stop selling them.

What kind of wood are you burning and how big are the pieces? If it has a high moisture content or really large pieces it will burn slower.

If you can measure your temperature drop and know what GPM you are pumping you can calculate how many BTUs you are using real easy.

[muffin]

My wood is fairly green.  It is not dripping sap or anything like that, but has not been aged.  I cut it to about 20" long and split anything over about 12" diameter.  I  typically do fill it pretty full, like up to the top of the door.  I do not try to shove it up higher.  I tend to leave the sides too so I have more of a pyramid shaped stack.  Doesn't seem like they really burn over there anyways.

I had the Taco 9 pump which is speced to 8 GPM.  I am upgrading that to a Grundfos UP26-99F which goes up to 34 GMP per the manufacturers recommendation for the desired flow rate for my pool heat exchanger.  This seems like it will make it worse, but maybe not.

I am wondering if with the new pump the fire will pretty much stay on while heating the pool and therefore not die down so much between heat cycles.  It really should heat the pool in 2 hrs max, not 8 like it is now.  I guess I will find out when my new pump arrives.

If that still doesn't work I guess I'll try the blower.  Sure seems like it cools 400gal of water awefully fast.

[Ridgekid]

Muffin-

Do you stack it that high in the front and back? I know your CB is much larger than mine, but I have only stacked, as you described, in front of the door. I've opened the door during a burn cycle and it appears as the fire exits the "pyramid" it rises towards the ripple top. I was afraid if I stack it too full I would force too much heat up the stack.

I cut my wood to about the same length. But I split anything under 8" round. You might get more BTU's out of your wood, since it's a little green, if you split the 12"ers.

Just thinking out loud here.

[muffin]

Front only too.  I was looking at that top ripple and thinking the same thing.  I try to keep it all as close to the door as I can.

[RSI]

The unseasoned wood is most likely the problem. You can't get anywhere close to the rated BTU burning green wood on any wood burner. Forced draft works much better on wet wood.