Harman pb105 Temperature question

[Chris04626]

HE said he hooked the pelelt boiler up so if it runs out of pellets and stops the oil boiler will automatically come on to keep the temp where its supposed to be set. I dont know anything about plumbing or what a zone valve is lol

I was told there is a open zone where another zone can be run from it, this was all there before the pellet boiler was installed.

 

[Chris04626]

there are more pics of the set up here http://s1131.photobucket.com/user/Chris04626/library/

 

[Chris04626]

what exactly does the outisde air sensor do?

 

[MaineMike100]

Hard to tell what's what with the pictures. Is this set up with the pellet boiler circulator running continuously keeping the oil boiler warm? If so could be some rather large standby loss up the flue of the oil boiler.

I 2nd the suggestion to get the installer back to explain/discuss. Nice boiler, does seem rather large for your described heat load.

Good luck w/ the adjustments, and luckily you have a little time to get the bugs worked out before it really cools down.

 

[Chris04626]

Yes i believe its set to keep the oil boiler warm. I am not understandign why it works great the first few days without using much pelelts but ever since its using more pellets and heating the baseboards, therefore making the house rather warm

 

[MaineMike100]

what exactly does the outisde air sensor do?

Not sure what the installer's intention was w/ your system, but usually it's used to vary the boiler temp as needed. Lower when the outdoor temp is warm, higher when it's colder. Saves fuel by only heating the water to what's necessary. Do a search for "Outdoor reset" and you'll find lots of info.

 

[Chris04626]

he said he hooked it up similar to the way you would hook up a regular wood boiler.

 

[Chris04626]

Just sucks it seemed to be running fine for a couple days then started using more pellets and heating the baseboards when the thermostat wasnt calling for it

 

[__dan]

From the pictures the both boiler return lines clearly parallel off the load return lines. Looks like that red pellet circ may be on with power from the pellet aquastat. That zone valve is powered when the transformer gets power.

With the zone valve open, there's probably parallel ghost flow through the other boiler, and the question would be what kind of parallel ghost flow is happening when DHW calls with one boiler then the other.

Heat is not my trade, professionally. If I was onsite for a couple hours I might figure it out, but not remotely. What I am seeing is a job I would not be competitive on. An honest opinion, so no apologies for it.

My suggestion is to do what I would have to do as a troubleshooter. Spend hours watching it run with various scenarios, heat zone calls or DHW calls, and with either boiler. Touch your hand gently to the pipe without getting burned and see where the heat is going, follow it, where it goes and is not supposed to. Read the gauges and if you have a noncontact IR thermometer, use that. Watch the boilers run and see if they are running they way you expect or they are doing something you don't want.

With two sources (boilers) and three loads, (one baseboard zone, DHW, and ghost flow through the other boiler) you have mathematically six possible operating combinations, some of which are wrong. I would have to watch it run to see what it is doing before making a diagnosis of what is next.

I'm also not familiar with the Harmon, and if it has modulating fire rate turndown. I do know what I would be looking for if I was to bid that install, but I don;'t want to say something at this point that would start conflict with your contractors (not enough information).

First make sure both boilers can be off with no call for heat. Turn the house stat off and wait for DHW to be satisfied, or turn it off. Make sure the boilers can go cold. Then call one load at a time, watch the boilers fire, where the heat goes, and if it goes somewhere it is not supposed to.

 

[Chris04626]

The guy that installed it is one of the best plumbign and heating guys around, however this was his first pelelt boiler install he has done many wood boiler installs though and was in contant contact with a tech at the dealer making sure what he was doing was right, so im unsure. What puzzles me is the thermostat has been set to 61 or 62 since its been installed and it hasnt been cold enough in here to get below that to make it call for heat. and wit hthe first few days it ran like it supposed to of. not spilling heat to the baseboards.

I have watchedd the pellet boiler and as its set to the minimum water temp of 140. So when it drop below that the boiler will light up and you can feel all the pipes get hot, and you get heat to the baseboards as well. Once it heats up enough it shuts off, then the temp will drop back below 140 and it will turn back on.

IS it normal for the water temp to drop below 140 so much?

 

[__dan]

I have watchedd the pellet boiler and as its set to the minimum water temp of 140. So when it drop below that the boiler will light up and you can feel all the pipes get hot, and you get heat to the baseboards as well. Once it heats up enough it shuts off, then the temp will drop back below 140 and it will turn back on.

The pictures say you have the Boilermate indrect tank for DHW. I see no reason the boiler would be set to maintain minimum water temp, the boiler should be off and cool to ambient if there is no call for heat from the loads. I'm looking for the reason.

If the boiler fires to maintain 140 while the loads are idle, there's a lot of unnecessary fuel consumption there, and you're saying you see ghost flow as the boiler fires to maintain with no heat call.

I'm wondering if it is set to maintain hot with no load because of the delay in firing to on with a DHW call. I don't know enough about the system to say, but if so, that would be no go with me. The other poster mentions storage with the Harmon.

Usually a boiler with a tankless coil for DHW will be set to maintain itself hot. A boiler with an indirect tank for DHW should be able to cold start, go off and cool to ambient with no heat call.

I would need to research further into the Harmon's operating requirements. If I was troubleshooting it, I would be on the phone with the factory.

 

[heaterman]

So from what you have said so far........

The pellet boiler is hot all the time 24/7
It also keeps the oil boiler hot enough to not fire
Your baseboards occasionally get warm even when there is no call for heat from the wall thermostat
You're going through a bag of pellets per day just maintaining water temperature.

From those things I can tell you the following facts, beyond them I don't know and can't tell from here.

*A bag of pellets = about 330,000btu or about 2-1/4 gallons of oil.
*That is a lot of heat going somewhere
*You need to get your installer back there and have him figure out what is going on
*Leaving it the way it is might wind up costing you more than burning oil.
*Heat coming out of the baseboard means that there is hot water flowing through them
* I have a hunch the pellet boiler circulator is creating unwanted flow in the rest of the system somewhere and somehow.

That's about all I can do for you unless you want to pay mileage charges from Michigan
Wish I could put my finger on it but I can't tell how exactly the installer set it up to work.

 

[Chris04626]

On the Harman controls it has a thing to set maximum and minimum water temp once it falls below the minimum it fires up to get back above the minimum

 

[heaterman]

On the Harman controls it has a thing to set maximum and minimum water temp once it falls below the minimum it fires up to get back above the minimum

That operating control is pretty standard on any boiler. The issue is, why is it set up to be hot even when there is no call for heat. Something is just jumped out and "calling" the pellet boiler on 24-7. That does not need to be like that unless there is something going on that I don't know or cannot see in your pictures.


Your installer can possibly help you with that or maybe a phone call to Harmon would clarify things for you.

 

[maple1]

Wouldn't the bigger issue be, why is heat being distributed when there is no call for it?

Or I guess maybe both issues combine to create one big problem.

 

[Chris04626]

Once it gets so hot it stops feeding fire goes outblower runs for awhile then stops then temp falls below 140 and it starts all over again.

 

[__dan]

I looked at the Harmon manual. Both the lack of information for necessary features and what the manual did say (boilers in series are one of the two factory plumbing recommendations) would have me on the phone with them.

The low limit temp setting is also the off switch according to the manual. The call for heat is a manual adjustment. There was no terminals provided in the factory installation manual for a thermostat call for heat.

Short cycling to maintain temp at no load will be bad for the boiler and worse for efficiency. The manual repeats many times, return water protection to maintain 140 return is required to prevent firebox condensation and warns many times to check the flue twice weekly for creosote buildup.

My read of this information is the Harmon is not an automated design and the factory must know this. It is the operator's, owner's, responsibility to turn the unit on manually when there is load and turn the unit off manually when there is no load. The manual does not say, 'do not let the boiler short cycle this is bad'. The manual does say to check and clean the boiler twice weekly, requiring the operator to manually attend to the boiler's burning.

The manual repeats many times it is the qualified installers responsibility to design the implementation. In my opinion this is not true and not standard in the industry. It is the factory's responsibility to design the standard implementations and for the installer to follow the manufacturer requirements.

If it were me I would be on the phone with Harmon for some answers and guidance, and if the answers prove hokey, like the manual, would be beating on them a little over the phone (boilers in series???, creosote formation in the flue ???).

I usually take a holistic, intuitive approach at design. What is it the owner wants to have done and will this equipment choice and implementation achieve that. Heat is a critical primary function that runs in auto unattended. Harmon states in their own manual that the boiler cannot run for more than two weeks without maintenance, and the manual has obvious previous generation, obsolete and inefficient, wasteful methods in it.

It is not the installers responsibilty to design and implement around the factory's deficiencies. The cost of that may be more than the installed cost of one of the more expensive european automated pellet boilers.

 

[Chris04626]

Plumber came down this morning and said a wire came lose which made it call for more pellets and heat then needed

 

[heaterman]

Wouldn't the bigger issue be, why is heat being distributed when there is no call for it?

Or I guess maybe both issues combine to create one big problem.

That too Maple, but if you eliminate the constant call for heat the unwanted "ghost" flow would disappear or at least moderate to the point it shouldn't be too much of a problem.
Reading through the Harmon lit that I have it doesn't appear that the boiler has a thermostat connection in the first place. It appears to me that it just cycles on the aquastat between 140 and 180* as long as power is on. Not a good situation.

 

[Chris04626]

It has ran fine since he fixed it no where nearas many pellets

 

[STIHLY DAN]

It has ran fine since he fixed it no where nearas many pellets

Glad you have it fixed. May not want to run it till the cold weather gets here, save some cash. Or take your boiler mate, buy a heat pump water heater, and tie them together. Never need oil, and wont burn pellets till its cold. Pay back would be less than a year.

 

[Chris04626]

Ok question is this normal?

IT was 63 in here i turned thermostat to 67 heat came on and its now 68 in here so thermostat turned off, i go downstairs and look at the boiler and the temp on that is a little under 140 and theres a fire and pellets are feeding every 5 seconds.

If the heat was on shouldn't it have heated the water? Why is temp on boiler showing under 140 still which causes it to eat pellets and continue to run?

 

[__dan]

Your pictures do not show boiler return water, low temp protection. If you cycled the heat a little and passed the cooler return water from the loads straight into the boiler, that lowered the boiler temp below 140 and it's firing to recover.

Boiler return protection is either a pumped bypass from supply to return or a loading unit, a three way thermostatic protection valve like the Akaso 810. Your manual says something about that.

I would says there's still not enough information to says what is and is not normal, for both meeting your demand economically and what the factory scenario for its customers is.

 

[Chris04626]

i see it has something called a grundfox x that is a circulator or something isnt it? What is the knob for you can turn on it?

 

[maple1]

Sounds like a 15-58 3 speed circ pump. I would leave it as it is if it is on speed 1 now. If it has problems moving heat from the boiler to your rads when winter comes maybe up it to 2.