Benjamin Wood/Oil CC500 help

[Dowielama]

Hello,
Hoping someone(s) can help. My family & I are in a rental and the owner informed me to use the wood option on the furnace. So I've been trying wood for a few weeks and have recently moved to bio bricks. I've loaded the wood chamber up and get it cranking with the bricks where the temp reads over 200. When the heat kicks on, I still hear the furnace going on. Is this normal? I feel like I'm just wasting $$ on wood/bricks if I'm still using oil. Any help would be appreciated.
Thanks

 

[brenndatomu]

Howdy! Where is that 200* temp from? You say the furnace still runs, you mean the oil burner fires up while the wood fire is going?

 

[maple1]

No, it's not normal. Sounds like you need to change some aquastat settings.

I ran one of those things for 17 years in my house, up until a year & a half ago - I'd also say it's not normal to get it up to 200° in this weather. I had a hard time seeing 170 most of the time. You might have a small place though that's easy to heat?

The manual should help with the settings - sounds like the draft door on the wood side needs to close earlier, and the oil cut-in needs to be lower. One thing I will give that unit - it was fairly well controlled.

 

[Dowielama]

Brenndatomu - The temp/psi gauge on top of the furnace. And yes, the oil burner fires up while the wood section is on

maple1 - I was looking at the aquastat and was wondering if I should tinker with it. So would I be lowering it? Does that tell the oil when to cut in?
With just the oil, the temp can get close to 200 but it doesn't stay up that long. Most times it sits around 170-180degrees. The house we're in is a pretty open floor plan and about 2500sq ft with 2 zones.
I just had to get another oil fill up after 4 weeks. I'm not liking the oil thing after years of living in s smaller home and have a pellet stove.
I'm just trying to get my head around how this unit works and the owner (who lives in Fla) has been almost no help. There's no manual to refer to either.

Thanks to you both

 

[brenndatomu]

Oops, I thought the CC500 was forced air furnace.

 

[maple1]

I still am using all the controls off my old cc500 - I just transferred them over to my new system. I forget now exactly, and this is mostly from memory, but I think the oil cut-in was the high adjustment on the aquastat on the side of the boiler. Maybe pop the cover off and see what its set at. I think I used to run mine set at 150, with the diff set at 20. So that would make the oil cut in at 150, and cut out at 170. Did you try googling the manual? Sure it's not stuck in a hiding place somewhere around the boiler?

 

[hobbyheater]

Does the house have two thermostats for each Zone ? If the house has only 2 thermostats turn each of them up and down separately to see if one controls only the oil side .

http://www.benjaminheating.com/prod...s/cc500-combination-oilwood-hot-water-boiler/

The units information tells me there should be separate thermostats for the wood and oil .

 

[Dowielama]

OK, so what's the diff? i.e. "diff set at 20" I can see the dial with 2 marks someone must have put on it. 1 @ 150 & the other 180. I just found the manual too, thanks

 

[Dowielama]

Does the house have two thermostats for each Zone ? If the house has only 2 thermostats turn each of them up and down separately to see if one controls only the oil side .

No- only 2 thermostats. 1 up & 1 down

 

[maple1]

OK, so what's the diff? i.e. "diff set at 20" I can see the dial with 2 marks someone must have put on it. 1 @ 150 & the other 180. I just found the manual too, thanks

There should be a 3rd dial in there labelled 'diff' for differential. I think the 'low' dial sets the temp at which the circ stops pumping. I think I had mine set at 140.

 

[Dowielama]

There should be a 3rd dial in there labelled 'diff' for differential. I think the 'low' dial sets the temp at which the circ stops pumping. I think I had mine set at 140.

Huge help I just went back down and looked and found the "triple" aquastat on the side. I had only found one that was sitting on top of the furnace. SO now I see what you're talking about.
So I put high on 150 (was on 180), put the diff dial on 20 (it was on 15) and the Lo on 140 (was on 150). We'll see how that works. Thank You

 

[maple1]

Generally, when I had mine, I was doing all I could to prevent the oil from kicking in. So I had my oil settings set low, and was a slave to the boiler doing wood. It is very inefficient on the wood burning side - all you have to do is look in the fire door and see the outlet to the chimney on the other end of the firebox to see that. But if you can displace oil with it, that's good. In order to get the most heat I could out of my wood, I had to damper down the flue pipe & draft with a key damper to try to slow down the exit of heat from the firebox to the chimney & give it a little more time to transfer heat to the water jacket. That has a bad side effect of increasing creosote deposits in the flue pipe & chimney. And I was constantly fighting a buildup of coals in the firebox that would take forever to burn up, being constantly washed by the water jacket on the bottom - there were some times I had no choice but to shovel out a ton of BTUs in the form of live & unburned coals just to be able to get more wood in the firebox. Well, I guess I did have a choice - let the oil burner run for a while. But that was like nails on a chalkboard for me whenever it kicked in. So, if you stop burning wood, you might have to set your aquastat settings back up so the oil will keep the boiler hotter - and please check your flue pipe & chimney regularly for creosote. I had to clean mine at the beginning & end of heating season, and twice in the middle. Do you have a barometric damper on the smoke pipe? If so, you can peek in there once in a while to check for creosote, and also clean some out thru it - but that's not a substitute for the regular cleanout points & procedures.

On the top aquastat, I'm a bit fuzzier on that. I think the HI setting is the temp at which it dumps heat in the case of an overheat, and the LO controls the bypass circulator. But that might not be right - there should also be a third single aquastat up top that might have controlled the bypass cirulator. So I'm not sure what the LO does now. It might come to me later.

 

[Dowielama]

Again thanks for the feedback. If this were my own home I would try to do what I could to increase eficiency, but since this is a rental I can't tinker too much. Boo
And did come across the manual finally tucked behind the hot water heater. Great place for it
After making the initial tweaks to the oil triple Aquastat, as mentioned above, things were going OK, or so I thought.
I found this morning that with the oil aquastat set at HI of 150, Low of 140 with a 20 DIFF, we were only getting a few mins of heat blowing into the main floor.
After about 5 mins only cool air was blowing through. So the oil burner wasn't going on, but no heat was coming in.

As much as it is killing me, I adjusted the oil aqua back up to a hi of 170, low of 160, 15 DIFF so we could get some heat.
I also discovered the Wood Aquastat on the top of the furnace which was set to the levels the manual suggested HI 200, Low 180.

Any ideas what the single aquastat on top of the furnace is for? or should be set to.

As this oil burner is on, I only see $$$ being burned ugghhh

 

[maple1]

Yes, that occurred to me later. One of those top sats controls the damper on the wood fire. I forget which one but I think it's either the low or high on the double. But isn't there a diff setting in that double stat too? I just checked mine & mine has one. So, the double & single stats on the top control three things - the boiler temps the wood draft door opens & closes, the over-hot temp that the boiler would dump extra heat at, and the upper temp at which the bypass circ comes on. I can't remember for sure what does what - but I'm thinking that the single stat does the bypass circ on the loop on the side of the boiler. That bypass circ I think is just there to maintain a more even heat in the boiler & help avoid thermal shocking. I think I had mine set around 180 or so - when temp gets up to that, the bypass circ starts & sends hot water right to the bottom of the boiler to mix with the colder zone return water. Mine had no diff setting, it was built in so you couldn't adjust it - I think it was around 15° or so. So the bypass would stop running when the boiler top temp dropped 15° from when it kicked in at.

The low setting on the side aquastat that you're playing with determines when the main circ will stop pumping - it will stop when the boiler temp drops to the setpoint. That is to allow the boiler to recover itself from a low temp. I think you'd still get some heat with water down to 140 or so, so that's likely what I'd try for that - although don't know what you have for heat distribution system. So maybe 140 might not be high enough. The HI & diff combination you will have to tune in yourself - it will mainly come down to how much time you can put into tending the wood side of the fire, and how cold it is out. The very poor efficiency of the wood side of this boiler makes it a challenge to try to avoid using any oil, and keep your house warm enough.

Also, I'm still not sure on the side HI & diff settings - my memory isn't what it used to be. It could be possible that the HI is when the oil cuts out, and the diff is how much it will fall before it cuts in again. So with a 170/15 setting, it would keep the boiler between 155 & 170 on oil. Watch the boiler temps & how it's acting & you should be able to figure it out, if the manual doesn't specify. Whichever the case, you'd likely want the LO setting to be lower than the minimum boiler temp, or else the circ will stop pumping while there is still good heat in the boiler. You might be good now with the way you have it set though.

 

[Dowielama]

I did find out instructions/guidance on the triple stats so that was helpful It took a few times of reading and re-reading but I get it now.
The fact it's in single digits probably isn't helping either. I'll keep playing

 

[ignots]

I also have a Benjamin CC500 and became very frustrated with maintaining a hot fire yet hearing the oil burner kick in. The aquastat on mine can only be set to a low of 110 degrees, no lower. The guage at the top of the boiler is a different reading from a different location on the boiler so it can be deceiving. I just had a switch added to the burner. Now I shut the burner off when I'm home and able to tend the fire. When we go out we turn the burner on and let the aquastat do it's thing. I should save a lot of oil now. By the way, my Beckett burner is making bearing noises and it's only 2-1/2 yrs old.

 

[maple1]

Does your house stay warm with the burner switched off?

I am not sure I would switch it off, if lowering the stat to 110 didn't stop it from running. That is a really low boiler temp, I don't think I would want it that low even if it cost oil to prevent it. The lowest I set mine to was 140 I think - I added the switch for those times the stat momentarily saw temps below that, like if the fire got a bit low & a couple zones opened.

 

[ignots]

It's been set at 110 since day 1 several years back. The guage at the top always reads higher. The other day I noticed the guage at 145 with a fire and the burner started up. House is very comfortable, in fact our upstairs level actually gets too warm. The installer made the upstairs the dump zone since we don't actually live up there. We're switching the burner off during the day if we can tend the fire, then turn it on at night.

 

[maple1]

OK - sounds like you've got quite a temp discrepancy going on there then. Which is kind of odd, it does have good aquastats on it. Maybe the well didn't get packed with thermal paste good enough, or a sensor tube is pinched? Long as you're warm & happy, that's the main things. I kept my burner switched off all winter - the sounds of it cutting in for 5 minutes at a time multiple times a day kind of drove me. Mine had a Riello burner on it though - that was the best thing about the whole boiler (even though I hated hearing it running). It worked like a top for 17 years, right up until I disconnected it. You might find a used one?

EDIT: Actually, now that I think about it a bit more - which dial on which stat do you have set at 110?