No Thermostats

Steamhead (in transit)

the boiler modulates or cycles in response to the outdoor temperature. This varies the water temperature which varies the heat input to the house. The TRVs control the individual rooms.

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Art M.

No Thermostats

I'm just a homeowner trying to understand the new system being proposed, but am looking for answers from someone other than my contractor. The proposed system is a Buderus wall hung boiler with pumping station and radiators with TRV's. I understand how the TRV's control the heat output in a room, but how does the boiler know when to fire up for heat without the thermostats?

Thanks

Art

steve b_28

just a homeowner who wants a better understanding...

Am I correct in understanding that with outdoor reset, the controller continually resets the boiler setpoint temperature, so that the boiler temperature rises as the outdoor temperature falls? And that one advantage with using outdoor reset in such a TRV controlled system is that most of the water from the boiler will go through the emitters rather than through a bypass loop since the supply temperature should be fairly close to that required to offset the house's heat loss with the TRV's wide open?


Also, wouldn't a system with TRVs and no thermostat operate as if there were a constant demand for heat so that the system circulator runs constantly and the burner runs until the setpoint temperature is reached and then runs again only when the boiler temperature drops to the setpoint less a differential (15 degrees standard with my controller, but may be variable with other controllers)?

As to how the boiler knows that heat is needed, I believe that my reset controller is programmed to run the circulator (and burner) only when the outdoor temperature is low enough that heat might be needed in the house.

Ted_9

GB142

The GB142 was first introduced to the US with the indoor room sensor. Its not an on/off t-stat, but a sensor. Using this indoor sensor, the GB142 almost runs in constant circ mode.

The GB142 will not just fire up with out a call from an on/off t-stat when using the newer outdoor reset control.

I personally would like to see the
GB142 with and indoor and out sensor and to run constant circ, like their R2107 control does for the cast iron boilers.

scott markle_2

outdoor reset

One of thing I don't like about the packaged outdoor rest on the budarus gb-142 is that the control is mounted inside the boiler enclosure.

To maximize the boiler efficiency it is desirable to set the reset curve as low as possible. In this case the trv's serve more as automatic room by room balancers or high limits than T stats. This setting can be found by fully opening the trv's and adjusting curve to the lowest point that still maintains desired room temperature. Curve adjustment is covered in the user manual(Viessmann), not just the installer documentation(Budarus).

I like the Viessmann Vitodens interface because it respects the intelligence of the home owner that may want to tweak these settings.By putting the reset interface inside the boiler it becomes very inconvenient and intimidating for the H.O to have any influence over these settings.However In reality most Americans would rather not "mess" with this.

In the case of the Vitodens if radiators are sized properly then Trv's are not even completely necessary. Yes wind and solar gain can effect indoor temp somewhat in such systems. However In the system that I did in this way indoor temperatures are very consistent with no indoor feedback at all.

The other nice thing about the vito is it's built in variable speed circulator. The Gb-comes packaged with a primary secondary piping arrangement (two circulators required).Your situation may not require this and running an extra circulator wastes electricity.

Don't get me wrong I have used both boilers,and I like the Budarus too, but for someone who is asking questions like you are the vito may be a better choice, it's interface and variable speed circ. are a perfect marriage to a panel rad system.

scott markle_2

Cold weather turn on

Ted, to overcome this could the boiler demand contact be wired to a outdoor thermostat such that below a set temperature the contact would be closed. Cold weather turn on as opposed to WWSD?

Do you think the reset control and boiler logic are capable of accurate space heating without indoor feedback in the way that the Vitdens can.

I ordered the indoor control for my last gb job for the reasons you mentioned. Multiple zones can be problematic with indoor sensor, I think that's why they switched.

I have novel approach to a basic two zone system that utilizes a remote trv and differential bypass.

Ted_9

sensor

I don't think that will work since it work of of the temp. Ideally, It wants to see room temp and maintain it. I'll respond some more tomorrow.

jalcoplumb_7

Very efficient.

> Am I correct in understanding that with outdoor

> reset, the controller continually resets the

> boiler setpoint temperature, so that the boiler

> temperature rises as the outdoor temperature

> falls? And that one advantage with using outdoor

> reset in such a TRV controlled system is that

> most of the water from the boiler will go through

> the emitters rather than through a bypass loop

> since the supply temperature should be fairly

> close to that required to offset the house's heat

> loss with the TRV's wide open?

>

> Also,

> wouldn't a system with TRVs and no thermostat

> operate as if there were a constant demand for

> heat so that the system circulator runs

> constantly and the burner runs until the

> setpoint temperature is reached and then runs

> again only when the boiler temperature drops to

> the setpoint less a differential (15 degrees

> standard with my controller, but may be variable

> with other controllers)?

>

> As to how the boiler

> knows that heat is needed, I believe that my

> reset controller is programmed to run the

> circulator (and burner) only when the outdoor

> temperature is low enough that heat might be

> needed in the house.



It is like a car and gas mileage. The longer run time will create a more efficient system. Like a car on the highway vs. city driving.

One of the most efficient systems is a mod/con with a closely tuned reset curve.

The system you speak of sounds very nice. You can control the room temps with the TRV’s and the boiler will do its thing based on the outside temp. If the indoor temp reaches design conditions the burner will shut down because there will be no change in inlet vs. outlet temperature.

Now if you have a modulating boiler, outdoor reset, and TRV’s and have the system sized and set up properly, you might be able to get the system to run constantly (ideal condition). This is not a bad thing. The burner will modulate up and down to use exactly the right amount of fuel to heat the home at that specific outside temperature. Very little waste.

Some people have a hard time with the idea with not having a traditional thermostat, but with the previously mentioned system you will have better control of your comfort with the TRV’s.

When the outside temp reaches a set temperature then the system will shut off.

jalcoplumb_7

Very efficient.

It is like a car and gas mileage. The longer run time will create a more efficient system. Like a car on the highway vs. city driving.

One of the most efficient systems is a mod/con with a closely tuned reset curve.

The system you speak of sounds very nice. You can control the room temps with the TRV’s and the boiler will do its thing based on the outside temp. If the indoor temp reaches design conditions the burner will shut down because there will be no change in inlet vs. outlet temperature.

Now if you have a modulating boiler, outdoor reset, and TRV’s and have the system sized and set up properly, you might be able to get the system to run constantly (ideal condition). This is not a bad thing. The burner will modulate up and down to use exactly the right amount of fuel to heat the home at that specific outside temperature. Very little waste.

Some people have a hard time with the idea with not having a traditional thermostat, but with the previously mentioned system you will have better control of your comfort with the TRV’s.

When the outside temp reaches a set temperature then the system will shut off.

Ted_9

Joe @ Buderus

Checks in periodically. He can explain the operation better than I.

Art M.

No Thermostats

So it is the outdoor reset that tells the boiler to fire up. But what about the zone valves? Do they still have a place in this type of system?

Ted_9

Outdoor reset control

I don't know how the GB142 comes now, but it used to be a control in it's own box. I would mount this ODR control to the wall. I never installed it in the boiler.

Ted_9

ODR

The ODR does not tell the boiler to fire up. Only some kind of heat call via external control, t-stat or Buderus room sensor will call the boiler to fire. Well, also a demand for domestic hot water if being used.

The ODR just tells the boiler what temp the water needs to be, to put it simply.

scott markle_2

zones

Art, the trv's provide zoning.However if the reset curve (which is the adjustable relationship between outdoor temp and circulating water temp.)is set low as I have advocated the upward adjustment of these valves will be limited. They become a means to lower room temp. but not to raise it above what the reset curve can deliver. Sophisticated systems Such as Tekmar tn4 overcome this by combining indoor feedback that overrides curve.

Conceptually you are right about ODR telling boiler to fire. However as Ted has mentioned this boiler requires a demand for heat (closed contact) to run circulators and fire.

A trv system is often designed for constant circulation. This circulation is turned off if outdoor temps. rise above a determined point usualy 65-70 (Warm weather shut down) or if heating mode is manually turned off.

I'm a little unclear on Budarus's recommendations regarding the wiring of this contact in a trv regulated application.
seems like wiring to a indoor thermostat wouldn't make to much sense except to setback during unoccupied periods.

Still it would be better to shift the global curve (as in vitodens control) than to put the system into bing-bang operation under setback conditions.

The gb reset control provides no convenient means for shifting curve for unoccupied setback.

scott markle_2

Your right

The box could be mounted out side the boiler. But it's set-up to mount inside, instructions show it this way, and connections would have to be extended.

I have never actually used the control,opted for Tekmar or Budarus indoor control.

Ted_9

Scott

Yes, it's just using 18/2 wire to connect fron the boiler to the ODR control.

Mike T., Swampeast MO

Am I correct in understanding that with outdoor reset, the controller continually resets the boiler setpoint temperature, so that the boiler temperature rises as the outdoor temperature falls? And that one advantage with using outdoor reset in such a TRV controlled system is that most of the water from the boiler will go through the emitters rather than through a bypass loop since the supply temperature should be fairly close to that required to offset the house's heat loss with the TRV's wide open?

You have a very good understanding Steve! Another BIG benefit of reset with a condensing/modulating boiler is that system temperatures (especially return temp) are kept nearly as low as possible which in turn keeps efficiency as high as possible.

With the Buderus GB driving a TRVd system, the RC-1 controller is likely the best to use. While the RC-1 resembles a thermostat, its operation is GREATLY different. The RC-1 attempts to produce a supply temperature just adequate to maintain the space temperature setting in the space where the RC-1 is installed. Change the space temperature setting and by monitoring the systems response over time, the boiler will learn just how much to increase or decrease the supply temperature based on how far away the desired setting is from the actual. The only drawback I see to this system is that because it can only sense room temperature in one room or area all of the TRVs in the other rooms/areas become true "slaves" and response to a TRV increase in the "slave" zones may be extremely slow. For that reason, I believe it best to install the RC-1 in a room/space that is slightly under-radiated compared to all others. A fully interior hallway without a radiator would likely be an ideal space for the RC-1 as such a space is technically a "slave" to the spaces surrounding it.

Also, wouldn't a system with TRVs and no thermostat operate as if there were a constant demand for heat so that the system circulator runs constantly and the burner runs until the setpoint temperature is reached and then runs again only when the boiler temperature drops to the setpoint less a differential (15 degrees standard with my controller, but may be variable with other controllers)?

That's very close to the way the Vitodens 200 (another exceptional boiler for use with TRVd systems) operates. There is however no truly fixed differential with the Vitodens--over time it adapts itself to the system to which it's attached and also to the way it is controlled by the user. The only flaw I see in this method is that when the boiler is adjusted for the most efficient (just barely adequate) heating curve, the only sure-fire way to quickly increase space temperature is to press the "party" button. At least in my system the Vitodens has done such a good job of learning and adapting itself that merely increasing the sun dial significantly does not give "quick heat". My Vitodens has been operating with a barely adequate and unchanged heating curve for 2 1/2 heating seasons now with nearly unbelievable efficiency. While I do keep the place cool (the "warm" rooms about 65F; the "cool" rooms about 58F), as closely as I can tell, the efficiency for the heating season as a whole is very close to 98%! I know that sounds almost unbelievable, but I've approached the calculations from numerous directions and they all agree.

Mike T., Swampeast MO

The outdoor sensor doesn't really tell the boiler to fire--it provides a target for the supply temperature. Should the actual boiler temperature exceed the target, the boiler will either modulate down or stop firing completely. If the actual boiler temperature is below the target it will either modulate up or begin firing.

TRVs are not "zone valves" in the way you are likely thinking. In most cases they are somewhere between open and closed--only rarely are they either fully open or fully closed. The boiler does not "see" zones--it only sees the system as a whole regardless of the individual TRV settings.

When directly connected to a fully TRVd system, the Vitodens genuinely acts as a real-time load sensing device without any form of user intervention. Unless the emitters are low mass (like baseboard) there is generally zero reason for any controls other than the TRVs.

The Buderus with RC-1 control uses a different approach as it varies target based on the difference between the desired and actual room temperature in the room/space with the RC-1 control. There is not outdoor temperature sensor.

Both are very good control systems for use with TRVs. The Buderus will optimize its heating curve without user intervention while the Vitodens requires manual adjustment--INTENDED to be done by the homeowner--of the reset curve and sun/moon dials to achieve the highest possible efficiency. Proper placement of the RC-1 may be finicky and special attention must be paid to system balance since the RC-1 becomes the "master zone" with all the reset "slaves". With the Vitodens there is no master-slave relationship among the zones. Primary/secondary piping/pumping is required with the Buderus GB, while the built-in variable speed circulator in some Vitodens models is often sufficient to drive a fully TRVd system without any form of primary/secondary.

While the method is somewhat different, both of these boilers can achieve system-wide setback via starvation of the TRVs. They will not necessarily stop firing as the room temperature falls to the lower setting--instead they will often continue to fire to a lower target. The TRVs will open wide but still be unable to achieve their setpoint and space temperature will fall.

scott markle_2

setback

Mike, by what means do you see the user achieving system wide setback with the RC-1?

I guess they could manually turn down the dial, fine for away for the weekend but very inconvenient for day night use. Much better to have a clock schedule that warms house slightly before wake up.

Also it seems to me that the the rc-1 the sensor would need to be in a reference location with no trv's. Is that what you mean by master slave relationship.

scott markle_2

not sure I agree

Seems to me that outdoor reset is preferable to indoor sensor modulated water temp. When trv's are incorporated.

In my opinion the two controls have the potential to conflict with each other. Turn down the TRV and the indoor boiler sensor will raise temp to compensate, thus over riding users intentions.

Mike T., Swampeast MO

You'll get system-wide setback with the RC-1 because it is striving to produce a supply temperature just barely adequate to meet the heat loss in the area with the RC-1. Presuming at least reasonable balance among the emitters, merely reduce the setting of the RC-1 and ALL of the structure will fall in temperature because the supply temp won't be adequate to maintain the "normal" room temp. THe other TRVs in the system have no way to tell the boiler that they cannot maintain the desired setting. This is setback via "starvation".

When the Buderus GB was first available (and ONLY with the RC-1 remote) I suggested that it would not be very well suited to multi-zone systems using on-off valves/circulators as it's really intended to be used with TRVs. From everything I've heard here, such is the case and Buderus fairly quickly offered outdoor reset as an option.

In a TRVd system using the RC-1 the radiator(s) in the "reference" zone (the one with the RC-1) typically won't have TRV(s) installed. An exception here would likely be for gravity conversions where leaving off TRV(s) can easily result in the affected radiator(s) "hogging" the flow due to essentially zero head loss while those with TRVs have quite measurable head loss. I have not used the Buderus GB, but still suspect that a fully interior hallway without a radiator would be an ideal location for the RC-1.

The master-slave relationship comes from the fact that the RC-1 will establish the supply temperature based ONLY on a single room/zone in the structure. ALL other rooms/zones MUST be able to be satisfied by this supply temperature. I'm positive that I recall reading in Buderus literature that the RC-1 is ideally located in a somewhat under-radiated zone compared to the rest. This gives the other zones some "headroom" for adjustment or unusual conditions.

Mike T., Swampeast MO

TRVs are incapable of directly telling the boiler or control system to do anything... They can only communicate with the system indirectly.

Both outdoor and indoor reset merely establish a "target" supply temperature. A modulating boiler will attempt to maintain this temperature as accurately as possible.

Reduce the room temp setting of even a single TRV by just a few degrees and the system load will decrease--unless the boiler reduces the firing level the supply temperature will exceed the target. The opposite happens when you increase a TRV setting. The is the "indirect" communication I'm talking about. The boiler and it's controller have zero idea that the user has changed a TRV setting--they just know that for some reason the system load has changed and that firing level adjustment is required to maintain target.

Done properly (as the RC-1 seems to do) indoor reset has the advantage of being completely self-adjusting while outdoor reset requires user adjustment. This self-adjustment comes at the "price" however of creating a master-slave relationship that does not exist when using outdoor reset.

With outdoor reset you can easily establish a curve significantly higher than is required by the system--unfortunately this is FAR too common as the reset curve in most mod-cons is designed for "professional" adjustment only. Since the pro isn't living there he'll typically use a "never have a callback problem" setting that's FAR too high. Comfort will be fine but the system won't be operating as efficiently as possible.

scott markle_2

user tweeks

Good point mike. Thats why I think the vitodens makes more sense for the user who actually cares and wants a role in how the system works.

Also for trv's to be upwardly responsive a somewhat higher than necessary curve is required.

For the efficiency minded a flow balanced and properly sized system with no trv's or prehaps trv's in bedrooms only is also an option this makes the Vitodens sun/moon dials real settings that can not be overridden by additional controls. and ensures that the lowest possible water needed to achieve desired room temp is being used. But you know all that.

Art M.

No Thermostats

Now that I am totally overwhelmed with information(LOL), tell me if the following assumptions are correct:

1 - The RC-1 controller sends the message to the boiler to fire up.

2 - The Outdoor Reset just modulates the firing of the boiler based on outdoor temperature.

Thanks

Mike T., Swampeast MO

Even with TRVs the sun/moon dials are "real" settings. Once you've established the proper reset curve the sun/moon dials are the maximum temp you can maintain anywhere in the structure.

I've corresponded with a number of homeowners with a Vitodens who have only the sun/moon dials for space temperature control. The only problem they consistently report is some overshoot in sunny rooms.

Mike T., Swampeast MO

The RC-1 does its best to keep the boiler firing continually. It does this by adjusting the supply temperature target such that it's just sufficient to maintain the space temperature setting in the control area. I can only assume that there is some "learning" involved that's mainly based on space temperature change over time.

Outdoor reset merely establishes a target temperature based on outside temperature.

Neither method sets the modulation level of the boiler--they only set the target. Other elements of the controls then modulate the burner to achieve target regardless of the current load on the system.

Sorry if I've confused you. Once you carefully observe a mod-con operating in a system without on-off thermostats, it's quite easy to understand what's going on--otherwise it's difficult to explain.

Art M.

No Thermostats

Thanks Mike, ever think of a career in politics? LOL The area in which we live lacks your high level of expertise. Ever think of an all-expense paid vacation in Maine? Seriously.

Best Regards

scott markle_2

\"real\"

By "real" I mean that if the user makes an upward adjustment to to the sun/moon dials, this can not be overridden by a trv.

Trv's in areas with solar gain or rooms that may want to be kept at lower than global settings makes a lot of sense.

Mike I'm still not sure why you prefer the RC-1 to the now standard AM-10. Seems like outdoor reset is immune to placement issues that would effect RC-1. Also outdoor reset has the benefit of anticipating increased heat loss. In other words if out side temperatures drop, circulating temps will rise immediately, (before indoor temps.are effected), (especially important in high mass radiant).It also works in reverse, if outdoor temps rise circulating temps fall avoiding wastefull overshoot that thermal inertia would cause. Indoor sensors alone, no mater how "smart" cant do this.

I know you are aware of this, and I'm not trying to lecture you I'm just trying to bring out the fine points on all of this.

I believe constant circulation could be achieved with the GB and am-10(ODR) by wiring boiler demand contact to a on/off outdoor thermostat such that below say 65 or so demand is activated. Do you see any problems with this? Please clarify the advantages you might see in the RC-1 arrangement. Yes global setback is not really available for Am-10, but the RC-1 gives no automatic scheduled setback option either.

Thats why I say spend a bit more for the Vitodens. By the time you strap a Tekmar control like the 270 to the Budarus so you can accomplish convenient scheduled setback and constant circulation outdoor reset (with optional indoor feedback) your getting close to the price of the vito. Add in the pumping station and the indirect circulator (not required on Vito) and the costs may be the same. Plus the Vito will probably run more efficiently and will use less electricity on account of it's direct piping arrangement.

Can I come to Maine too ?

Mike T., Swampeast MO

Scott:

I haven't used the GB. Is there no built-in setback timer like with the Vitodens?

I'm no fan of daily temperature setback; instead I prefer to constantly maintain the lowest temperature suitable for the use of a space (including "as low as possible" for rarely used spaces). In that regard, TRVs are a GREAT addition as you get all of the benefits of room-by-room zoning without the "micro-zoning" hassles that can occur if on-off zone control devices are used.

If I ever get the time and equipment (accurate flow sensor, BMS system), I really want to develop an add-on control for the Vitodens that allows it to sense user desires--especially in a TRVd system. I'm positive that all of the necessary information is contained in the water itself--all it takes is a couple extra temp sensors and some good programming. The German Viessmann engineers don't really consider this as an important goal as they seem to feel that it "pollutes" their masterpiece by introducing inefficiencies. Considering how their buildings are typically constructed (massive masonary with exterior insulation) I can understand their point, but American structures and lifestyles are MUCH different and unlikely to change too much in the foreseeable future.

Mike T., Swampeast MO

I've never used the GB, but it's that very inability of TRVs to tell the boiler, "Hey, you're making water that's much too hot" that makes me really like the concept of the RC-1 remote. It [may] be persnickity with regards to location and ideally will require some extra consideration of the system design, but the ability to produce a self-adjusting reset curve is awfully nice... This is the main advantage that I see of the RC-1.

I've talked to a number of techs at different companies producing mod-cons and ALL I've spoken with say that you can produce a system of true constant circulation by jumping the t-t connections (to produce a constant call for heat), using TRVs (or a very good reset curve) and [hopefully] adding warm-weather shutdown as well. I see no reason why the GB would be any different in this regard, but frankly I'd try it with the RC-1 as not only is it simpler, but it should be more accurate.

You won't go wrong with the Vitodens and if you design your piping carefully you don't even need the low-loss header or any additional circulator(s). Just that savings would pay for a number of TRVs...

I only work with converted gravity systems in old homes that have generally seen significant thermal improvement as well as some "modifications" over the decades. In this regard, TRVs are a near must since radiator balance (particularly on the upper floor(s)) is extremely poor and it's FAR easier and cheaper to add TRVs than to re-size and re-pipe radiators.

Someday I'd like to design/build a new system for use with the Vitodens (sans LLH) and with few (if any) TRVs, but with new residential hydronics incredibly rare in my area, I doubt it will ever happen unless I get tired of this big, old house and still have enough energy--let alone money--to build new. But with my ideal home using ICF walls, SIP roof, carefully sized/placed/shaded windows, passive solar orientation, active solar DHW, mix of radiant panels and oversized radiators, it would have to be ridiculously large to need anywhere near the output of the smallest Vitodens currently available.

While I'm quite partial to the Vitodens and sincerely believe it to be the finest and most efficient (as well as the best value in suitable systems) residential boiler currently available, I'm diplomatic enough to realize that other homeowners/contractors have different preferences and priorities. I try to point out the strenghts as well as weaknesses (as I see them) in EVERY mod-con.

Something tells me that the AM-10 control for the GB is only "standard" on this side of the pond... From what I could read between the lines in some conversations with Buderus shortly after the introduction of the GB, it seemed that the German engineers resisted offering outdoor reset as (just like with Viessmann) they believed it somehow "polluted" their masterpiece. Of course they made the same mistake as the Viessmann engineers in failing to properly consider North American construction methods and heating system design practices...

Mike T., Swampeast MO

Time is my problem. Hardly enough of it to do what I must do, let alone what I'd like to do...

scott markle_2

Were is Joe?

What does Joe@Budarus have to say on this?

No mike the Budarus does not have any clock functions nor does the AM-10 have a unoccupied mode contact that can alter the curve. The Tekmar 270 has no clock functions but does have a unoccupied mode contact that can be connected to a timer(tekmar makes one). It also has a optional indoor sensor that works with the ODR to fine tune/correct supply temp based on actual indoor temp. Nice option for the person that wants setback with the GB. I have used this control it works well. But you have to buy a separate EM-10 control to interface with 0-10 volt Tekmar signal.

I believe setbacks are valuable, less so in high mass radiant, but for panel radiators I see no reason NOT to use setbacks if occupants have regular work schedules and sleep behavior. Why should we heat space to comfortable levels and maintain high temperatures in indirect DHW tanks when no one is home. Why keep the living room etc. at 68 at night when we are sleeping at 62.

Well sized panel radiators are very responsive. Whats the down side to setback as you see it?

The GB is made in the Netherlands by Nefit/Budarus a Duch manufacture. It seems like a very well engineered piece of equipment, has a somewhat car engine appearance on the inside,interesting easy access spring clamps that open burner/hx, it's supper quiet, has a quality exterior appearance,vents through pvc and is significantly less expensive than the Vitodens

Still if the internal circulator on the Vitodens can supply the necessary flow and head, (very likely in home run 1/2" pex panel rad. arrangement.) Then in my opinion the Vito dens is a better choice. Also of note, the appearance of the direct connected vitodens can be very elegant largely because of it's built in circulator which is also used for dhw production. If the owners have modest dhw requirements and centralized compact plumbing the Combie unit with plate HX for DHW makes a good energy/space saving option. Just don't expect a high volume shower, endless though.

Although this is not exactly the elegant arrangement I was referring to. This photo may give you a sense of how much can go in so little space with this boiler. The Gb with it's Mandatory P/S piping and separate DHW circulator would have been very difficult if not impossible to put in this space. Most of the pex seen here is home run domestic water lines and this is a combie boiler.

Ted_9

BC10

The BC10 (main control) has an ECO setting for the DHW though. I don’t see an ECO setting for the space heating. I believe the domestic target is 140 degrees and waits for a significant drop in water temp before it starts making DHW again. I think I'll try this out for the rest of the summer. Note to anyone reading this; setting the domestic hot water temp to 140 degrees will require a tempering valve for hot water going to your fixtures.

Unknown

gb boilers

curious to know if anyone has tried the am10 for radiant
use, and if so have they tried to use the wa contacts
for high temp

Unknown

gb boilers

curious to know if anyone has tried the am10 for radiant
use, and if so have they tried to use the wa contacts
for high temp

Dread27

Throw an ECM pump into this mix and you have the best of both worlds with fuel consumption and electricty savings.

scott markle_2

two temps.

The am-10 works in conjunction with the wa contact. The rc-10 will fire the boiler and set temperature the wa contact is not used with the rc-10.

Some limitations of the gb: Mandatory primary secondary regardless of system flow rates, Very high dhw operating temp. (limited to 190) this is hard on glycol and the aluminum hx is extra sensitive to water chemistry. No timer functions for the am-10 or rc-10, user interface provides no simple(homeowner) adjustment of heating curve (shift).

Not sure what your getting at with the question, but if you are planing high temp and radiant you will need a mixing valve or injection bridge.

If your looking for a nice german boiler(gb is from the netherlands actualy) I would take a look at the vito 100 it's priced more in line with the gb and comes with no controls. Pair this with a tekmar control that suits your specific needs instead of trying to make the gb's package do something it may not be ideally suited for.

You can also dump the am-10 and buy an em-10 and operate the boiler off a 0-10v signal from a third party control if you like.