Weil Mclane ultra 155 settings

[ktm250rider]

I currently heat with an outdoor wood boiler. This maintains the water temp going through my WM-ultra at about 180°. The heating limit on the ultra is set to 150° as a backup if the fire goes out. At this setting, when the house calls for heat, the boiler does not fire. The readout says that the system is satisfied. When the hot water tank calls for heat, the boiler fires and maintains 190°. I have the setting on the DHW at 140°. Any idea why its firing to 190° when I have it set for 140°?

[larobj63]

I think I know what you are asking...

When the domestic hot water aquastat calls, most of the internal controls on the mod / con boilers automatically ramp the boiler output to 180 or 190 to maximize domestic hot water recovery. They also usually disable teh pump that runs through the boiler and feeds into teh heating loop, and enable a pump in-line with the indirect tank.

You could do some piping and controls trickery to heat the domestic hot water with the wood boiler if you wanted, depending on your ambition and budget level... In other words, if the wood boiler loop is over say 160, divert the water through the indirect tank with a three-way valve when the dhw calls. I would pipe the indirect tank "first" in series with the house radiation, to maximize the delta t between the domestic hot water and the water you are heating it with...

Sorry, I'm an engineer, I'm always thinking of better ways to do hydronic systems...

Otherwise, it sounds like things are operating how I would expect, based on what I know...

[qwerty hvac]

I think I know what you are asking...

When the domestic hot water aquastat calls, most of the internal controls on the mod / con boilers automatically ramp the boiler output to 180 or 190 to maximize domestic hot water recovery. They also usually disable teh pump that runs through the boiler and feeds into teh heating loop, and enable a pump in-line with the indirect tank.

You could do some piping and controls trickery to heat the domestic hot water with the wood boiler if you wanted, depending on your ambition and budget level... In other words, if the wood boiler loop is over say 160, divert the water through the indirect tank with a three-way valve when the dhw calls. I would pipe the indirect tank "first" in series with the house radiation, to maximize the delta t between the domestic hot water and the water you are heating it with...

Sorry, I'm an engineer, I'm always thinking of better ways to do hydronic systems...

Otherwise, it sounds like things are operating how I would expect, based on what I know...

I agree. We have a lot of these setups around here and that is pretty much what we do to solve this problem.

[beenthere]

Thats the setting from factory.

You can ask your contractor to reset it, if you want. if you don't have a high hot water demand, no problem resetting it to 170, maybe even 160.

I've set several lower then what the factory recomends. No problem, unless they have a high demand(more then 100 gallons in 30 minutes on a 40 gallon tank).

[larobj63]

Thats the setting from factory.

You can ask your contractor to reset it, if you want. if you don't have a high hot water demand, no problem resetting it to 170, maybe even 160.

I've set several lower then what the factory recomends. No problem, unless they have a high demand(more then 100 gallons in 30 minutes on a 40 gallon tank).

Well, right, but..

Depending on how it's piped, the DHW tank is likely a parallel circuit piped into the gas boiler injection loop, with checks in both circulators. If this is the case, piping changes need to be made in order to actually heat the dhw tank with the wood boiler loop. If he does what you describe, at least the gas boiler will be running more efficiently, in theory.

Would need either lots of photos, a schematic, or a site visit to know for sure. I'm just guessing at how this is piped, based on what has been described, and the near boiler piping schematics that usually come with the mod/cons.

[beenthere]

Since he said the wood boiler maintains the temp in the boiler.
I'm guessing its already piped up that no other modifications are needed.

[larobj63]

Since he said the wood boiler maintains the temp in the boiler.
I'm guessing its already piped up that no other modifications are needed.

Depends. The gas boiler system supply sensor could be in the wood boiler heating loop.

I was thinking the gas boiler is injected into the wood boiler heating loop, so you don't fight the head of the gas boiler all the time.

At least, that is how I would do it, but you would need additional complexity to heat the dhw with either source...

It could be either way, like I said, would need to see it. :angel:

[beenthere]

The sensors of the Ultra, ain't reaching a wood boiler that is installed outside.

[larobj63]

The sensors of the Ultra, ain't reaching a wood boiler that is installed outside.

I haven't dealt with WM as much as I have with Lochinvar.

Lochinvar boilers come with a remote system temp sensor, which you would install in the heating loop, not the injection loop.

Do the WM not have a remote system sensor? How else can it effectively reset supply temp?

I am assuming the wood boiler is right in the main heating loop, and the gas boiler is set up as an injection loop into the main heating loop. In this case, you would put the system supply sensor in the main loop, this would let the gas boiler know if the main loop needed heat or not. Kapeesh?

Again, this is how I am imagining it, because it would minimize pumping energy. The same would apply if the wood boiler is injected into the main heating loop. You would still want the gas boiler system supply sensor in the main heating loop.

[beenthere]

The Ultra monitors its return and supply temp. And an outdoor sensor. And adjust its temp.

The heating loop temp doesn't need to be monitored. Since if the reset temp is high enough to heat the house. then the loop temp must be correct.

Why use a remote, and let the boiler get hotter then needed.

[larobj63]

The Ultra monitors its return and supply temp. And an outdoor sensor. And adjust its temp.

The heating loop temp doesn't need to be monitored. Since if the reset temp is high enough to heat the house. then the loop temp must be correct.

Why use a remote, and let the boiler get hotter then needed.

Plenty of reasons.

When you use a mod con to heat a home (even as back-up) AND heat domestic hot water, you want it piped as an injection loop, so when the dhw calls all summer long, you only heat the dhw tank and boiler as an isolated system.

If you gang boilers together, you want the system loop temp, not the temp from each individual boiler.

Been - look at the hook-up diagrams in the WM manuals, I just did. They use a supply and return sensor in the main loop, NOT the injection loop. They are remote sensors.

Mod cons are almost always suggested to be primary / secondary. You should sense the secondary loop (heating loop), not the primary, when using OAT reset.

[beenthere]

Still don't need loop sensors when piped as injection. Even with DHW.

I only use loop sensors if I'm piping up multiple boilers. And I use the BCP control from WM then.

[larobj63]

Well, if you had two heat sources, a gas and wood boiler, and the gas boiler were piped as an injection loop, you would certainly want a system sensor! Otherwise, the back-up gas boiler has no idea if the loop is under load or not! lol

If you are piping the main loop right through the gas boiler, the dhw hookup would be a compromise, insofar as it would not be isolated in the summer. And, like I said before, you would be needlessly fighting the gas boiler head all the time.

[beenthere]

You can pipe an Ultra up without primary/secondary piping. And not have any problem with the DHW loop and heating loop conflict with each other.

Got a couple like that. Use 2 circs, and 2 flowchecks.

[beenthere]

Your making it out much harder then it is.

[larobj63]

You can pipe an Ultra up without primary/secondary piping. And not have any problem with the DHW loop and heating loop conflict with each other.

Got a couple like that. Use 2 circs, and 2 flowchecks.

If it is not primary / secondary, you are constantly pushing through the gas boiler, which is a waste.

I am not over complicating it. There are many ways to do hydronics, not every way is the best way. There is a reason all the hookup manuals show primary / secondary for mod cons, and there is a reason they all show system sensors in the heating loop, not the injection loop. It is pointless to say you can do it this way or that, of course you can pipe it 110 different ways, most of which will work, and only a few of which will perform perfectly in every scenario and save pumping power.

Anyways, we are both speculating about what the OP has.

[beenthere]

Primary secondary piping is to ensure proper GPM through the boiler. thats it. No other special reason.

What page is it showing to use remote sensors on a single Ultra boiler application..

[larobj63]

I'm looking at their install manual for gas series boilers - Series 3. Page 16. Shows sensors in the main loop (numbered 10 in the schematic). In fact, it shows the sensors in the main loop for all the different system types in the pages that follow. Lochinvar does the same thing, but only uses a system supply sensor, not supply and return sensor. It looks like Munchkin temp sensers are in the boiler, like you describe, but I'm not as famliliar with them.




Primary secondary piping is to ensure proper GPM through the boiler. thats it. No other special reason.

That is simply not true. :couchhide: It allows there to be flow through a main circuit without fighting the head loss of the heat injector (or rejector), except for when you are using the heat injector (then, its dedicated ciculator overcomes the head through the heat injector). Which is directly relavent here, because there are two heat sources, wood boiler, gas boiler.

Boiler / chiller heat pump loops are commonly set up this way for this very reason. No need to fight the head loss of the chiller all winter, and no need to fight the head loss of the boiler all summer. They're not all set up that way, just the intelligently designed ones. :troll2:

Plus, unless it is truelly a single zone system, the primary secondary will do what you said - ensure proper flow through the boiler, independent of how many zones are calling.

[beenthere]

Those are optional sensors. Not required.
And only used on the U line module. The series 2, and 1, didn't even have provisions.

Since were talking residential. And most homes don't have chillers. I'm leaving HCW systms out of the conversation. But, the water flow is diverted so the boiler doesn't condensate in the summer from the chilled water. Its not a flow issue.

Since your injection piping is less then 12" apart. There is no head loss, or battle when the boilers circ runs. Since the same amount of water the circ would pull into the boiler, Is the same amount that it puts back into the pipe. And the pipe between the 2 points flows the smaller amount of water that is the difference, between the 2 flow rates.

[larobj63]

Those are optional sensors. Not required.
And only used on the U line module. The series 2, and 1, didn't even have provisions.

Since were talking residential. And most homes don't have chillers. I'm leaving HCW systms out of the conversation. But, the water flow is diverted so the boiler doesn't condensate in the summer from the chilled water. Its not a flow issue.

Since your injection piping is less then 12" apart. There is no head loss, or battle when the boilers circ runs. Since the same amount of water the circ would pull into the boiler, Is the same amount that it puts back into the pipe. And the pipe between the 2 points flows the smaller amount of water that is the difference, between the 2 flow rates.

I don't think you are understanding me. This could be my loose use of terms, or it might just be I have a better understanding of hydronic principles. :angel:

An injection system IS a primary / secondary system. The primary loop is the boiler loop, the secondary loop is the system, or heating, or "main" loop.

If we are clear on the terms, then you are condradicting yourself. All fittings and heat exchangers and pipe lengths have a presure drop, or head loss. I am quite sure you know this. The statement "There is no head loss, or battle when the boilers circ runs. Since the same amount of water the circ would pull into the boiler, Is the same amount that it puts back into the pipe." is not true. If you have a primary and secondary loop, you have de-coupled the systems. The secondary loop pump is not designed to fight the head of the boiler. (Well, it certainly would usually have the ability, but it is NOT doing this work in reality) The primary pump IS fighting the head through the boiler, it IS actually doing this work. This is why the bypass is there. When the boiler is off, the system (or secondary or heating loop) pump happily moves water past the boiler injection loop without any parasitic drag. It's the whole reason everyone says "less than 12" apart", or "less than 8 pipe diameters", etc. This ensures the pressure difference between the two connection points doesn't induce flow, or otherwise influence the water movement in the circuit not being used.

When you have a system with multiple heat injectors or rejectors, it is common to use de-coupled, primary / secondary systems. The main circulator is designed to move water around in the main system loop, and depending on the zone strategy, maye through the heating circuits / terminal units as well. This is all it is designed to do. The injection circulators are designed to overcome the head in their respective boiler or chiller or whatever it is. This is all they are designed to do - but realize that it is work being done! If there was no work being done by that circulator, you wouldn't need it to be there, you would use a diverting valve!

You can not say that there is no benifit to doing this. You can not say "the only reason to do primary / secondary is to garuantee a flow through the boiler" That is wrong. If all the heat injectors were in series in the main loop, whatever pump is used to pump through them all would always have to push through all of the appliances, all the time, weather they were being used or not. This wastes pumping energy, because the pressure drop through each appliance puts drag on the system and makes the one pump work harder, again, needlessly.

I brought up heat pump loops because it is a common application of decoupled (primary / secondary) loops. To further the reasoning of why they are injection set-ups in heat pump loops, and not just run through the boiler, it will protect cast boilers from thermal shock and low temp operation (the heat pump loop is kept between maybe 50 and 90). This is in addition to your reason that water could condense in the boiler during the cooling season. Kind of moot with mod / cons that like low temp operation, but then it goes back to my original statement that by de-coupling the boiler, the main system pump doesn't have to always push through it! But yeah, this is probably greying my point more than cementing it.

Now, let's put this all together. If you have heating appliances that are piped as injection loops (primary / secondary), and the appliances job is to maintain a temp in the secondary loop on a heat call, the sensor must be in the secondary loop! The water is not going through the boiler unless the boiler circulator is on!

If it is not piped as an injection loop, yes, the sensors could be right in the boiler. But with two heat sources - this is bad practice.

:yes:

[beenthere]

Primary can be done as an injection, or as its own loop system.

This is well outside the scope of the OPs question.

PS: You need injector controls to protect the boiler from low temp.
Primary secondary itself won't do it. Unless your using an oversized boiler.

[larobj63]

Primary can be done as an injection, or as its own loop system.

This is well outside the scope of the OPs question.

PS: You need injector controls to protect the boiler from low temp.
Primary secondary itself won't do it. Unless your using an oversized boiler.

Agreed, and true.

PS: True, but I was speaking in terms of piping, not including controls (not that I said that)...

I only got this far off topic because you brought up a few common misconceptions about piping during the on topic conversation. I have learned plenty from you been, but not in this thread. :ghug:

[beenthere]

There are many myths about what primary/secondary piping does.

It is not the end all that many make it out to be. But, the myths continue.

[larobj63]

There are many myths about what primary/secondary piping does.

It is not the end all that many make it out to be. But, the myths continue.

I have thick skin, so I'm not taking that personal. Hopefully you have thick skin as well. You are dead wrong with a few of your statements in this thread (which is a first, I am fast to say), and instead of admitting it, you say something like "the myths continue", which, certainly insinuates that I am perpetuating "myths".

Is it possible that someone knows something, or understands a concept more than you? :anyone:

[beenthere]

LOL...

I learn something new most days.
Many believe they understand a concept.

Myths are often perpetuated by people that don't know its a myth.

[larobj63]

LOL...

I learn something new most days.
Many believe they understand a concept.

Myths are often perpetuated by people that don't know its a myth.

Been, so let's hear it. What have I said that isn't true.

I took the time to point out the two statements you said that aren't true. Enlighten me what mythical principals I am believing in. I never said primary secondary piping is "the end all be all". I never said it is anything. I brought up that by using injection loops (or primary / secondary piping), you can save pumping energy, and I went on to expalin how. It is a basic principle, which, by your statements, I don't think you grasp. It is not a myth that by de-coupling systems you can save pumping energy. There is no need to run water through unused appliances. Every appliance has a pressure drop, which costs energy (money) to pump through. By de-coupling the applaince from the main loop, you avoid this pressure drop and save energy when the appliance isn't in use. This is what you're dealing with in any system with multiple appliances, like the OP's. If you can refute that statement, you are changing physics, my friend.

Sorry buddy, I am feeling a little miffed. I defend what I know to be true, and all you are doing is saying "yeah, all that stuff is a myth, and people that don't know it's a myth keep spreading the myths".

Well, people that don't understand concepts can just as easily call those concepts mythical. :argue:

:patriot:

[beenthere]

Not much head loss in a boiler.
Residential circs, are less then 200 watts an hour consumption, for a high head circ.

If boilers had a high head loss. That caused circs to use a lot of wattage. You wouldn't need to keep the tee's close together to prevent flow through them.

Since this was a thread about residential boilers. I'm not going into the benefits of P/S piping in commercial. But, it is also misapplied in some of those applications also.

But, it does not prevent thermal shock in residential applications. Unless the boiler, or its circ are oversized, And the circ is drawing the boilers discharge water in reversed flow in the piping between the tee's.

[larobj63]

Not much head loss in a boiler.
Residential circs, are less then 200 watts an hour consumption, for a high head circ.

If boilers had a high head loss. That caused circs to use a lot of wattage. You wouldn't need to keep the tee's close together to prevent flow through them.

Since this was a thread about residential boilers. I'm not going into the benefits of P/S piping in commercial. But, it is also misapplied in some of those applications also.

But, it does not prevent thermal shock in residential applications. Unless the boiler, or its circ are oversized, And the circ is drawing the boilers discharge water in reversed flow in the piping between the tee's.

Ok, ok. There isn't much head loss in residential boilers. But then again, there isn't much head loss in entire residential systems. It's all relative. There are plenty of home systems where the head loss in the boiler is greater than the entire rest of the system combined. Especially low mass boilers.

Primary secondary may be misapplied sometimes. Fine. And sometimes, it may be designed in for good reason. What's your point? I never stated there was any benefit that wasn't true, or perpetuated any myths. I think you said a few things that are flat out wrong, and some that are sort of true, so forgive me for getting jumpy.

To say that the head loss is low in a resi boiler, that is why the tee's need to be so close, is sort of true, but not the whole story either. Even a high-head appliance would have some induced flow if the tees are in different locations on the loop. Head is directly related to fluid velocity. Flow is induced until the pressure drop between the tees equals the pressure drop through the appliance. It doesn't really do any harm though, because no additional work is being done, just some minimal heat is lost or gained into the un-used appliance. If you put the appliance right in series with the loop, ie, not de-coupled, the full effect of the head loss through the appliance is realized, and you pay for it with pumping energy. You see my point?

Thermal shock - right, you would need a tempering valve to return some of the boiler heat / flow to the boiler. Primary / secondary alone does not do this, per se.

I brought up commercial applications because in commercial applications, you really should know how to avoid pumping energy, and there are plenty of good reasons to de-couple appliances from system loops, including (but not limited too) energy use. How many years have triple-duty valves been thrown in large systems with way-oversized pumps, and the static circuit setter is cranked down to get the flow the engineer asked for in the schedule? The company paying the bills gets to pay for that head loss for the next 30 years. Those guys knew what they were doing too, right? I know static circuit setters has nothing to do with primary / secondary, it's just another demonstration of wasting pumping energy, and how it used to be common practice when energy was cheap.

But the great thing is - the principles remain exactly the same in residential, just on a smaller scale.

Cheers.