Need some help from my friends...

Weezbo

i look and ok, is that a modulating mixer or a fixed mix?if you have a long washing machine hose you could connect it to the purge valve on the supply header and return header purge....crack the valves so you have some flow through it..let it run a couple hours like that ...and if its a fixed mix , also,dial it up to 5 and leave it there.

Constantin

Questions arise...

... I am currently sitting in a all-radiant house in Maine, where the heating system is throwing some questions at me. I hope that the collective wisdom of the Wall can help me further...

Attached is a system sketch that shows all the zones this system has. The primary loop is about 3" in diameter. The piping running to and from the Tekmar 010 is 1.5" Dia. The heating zones are fed by 3/4" dia PEX tubing.

All the pumps are Tacos and I indicated the models on the drawing. The system is run by a Tekmar 367 and 371, which controls two propane-fired Buderus G124X boilers. Both boilers are protected by LWCO's, BTW, it's just not indicated here.

The house is about 4000 ft², heated all-radiant, mostly under wood. The walls are filled with Cor-bond, though there are some large windows/french doors in one area. Unfortunately, the system seems to have some trouble keeping up despite having a lot of heating horsepower.

For one, I do not understand the piping with the 4-way Tekmar valve. I don't see how the primary loop is going to work with it well, particularly with 1.5' between the takeoffs and no pump to push water that way. It seems to heat, but in my mind, the piping between the takoffs should be blocked with a bypass valve.

Secondly, I wonder how well most of the house can be heated with nothing more than a 011. I suspect flow issues are holding back the system responsiveness, particularly in the more far-flung areas of the house. To the best of my knowledge, there are no additional circulators in the system, so the 5/16" piping under the floors upstairs may pose some interesting head pressure issues for the 011 pushing water through that system.

I can see the two boilers staging OK, though they bounce off the high-limit pretty quickly when both are firing. I suspect that is because the primary loop has (what looks to me like) a bad connection to the primary heating zones. The max. supply temp to the zones is around 140°F, while the boiler loop is running up to 190°F.

I would appreciate any thoughts you all might have. Many thanks!

hr

A lot of zv's

on one pump! Really need to know the flow and pressure drop of each zone to correctly answer your question. Possibly a heat loss and design would answer this question.

I'd like to see at least a PAB valve with that many zone valves, so the circ has a chance to adjust to varying loads.

Yes the 5/16" tube zones could be more than that pump alone can handle??

I'd like to see the boilers piped better so the flow only goes through the fired boiler. A couple ways to accomplish this.

While not ideal on the 4 way connection to the primary loop, it should work. The tees could be tighter.

hot rod

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Ted_9

Just as a note to everyone that doesnt have the chart. The 0011 can give about 28 GPM at 30 feet of head.

PATRIOT HEATING & COOLING, INC.

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Constantin

Good Points, for sure!

I am having many of the same thoughts as I compare my system (where every manifold has its own 15-58 circulator) vs. this one (where one 011 pumps into 7 ¾" circuits that have about 6 pairs of 5/16" tubing attached to each one). As best as I can tell, the designs are at opposite extremes as far as the usage of pumps is concerned.

I presume a PAB valve is a differential pressure bypass valve? This would be tied across the supply vs. the return of the zones, correct?

Considering that the 4-way valve is motorized (Tekmar 010) and has 1.5" connections, wouldn't it make sense to make it part of the primary circuit instead of using "closely spaced T's"? I was thinking we could either install a PAB or a simple ball valve to force most of the flow through the 4-way valve.

As for re-piping the boilers, how would you best do it?

Constantin

Thanks Weezbo & Ted!

The Tekmar 010 motorized controller modulates the temperature of the 4-way valve. The house has since come to temperature, but the response has been quite uneven at first.

I suspect that the higher head pressures in the more faraway places resulted in those zones getting hot water much later than the closer ones. Plus, the house was set back to 55°F until about 3 hours before we arrived. I also discovered that the installer did not install a insulation layer below most floors. That would explain part of the issue as well.

To give you an idea of the differences, the closest manifold is about 10' from the boiler room and consists of ½" pipes running into the basement slab (which is kept quite cool). The furthest runs are about 75'

Jed_2

Definitely agree with Hot Rod

With that many zone valves, and a 0011 Taco, a DPBV(DAP) is (IMHO), definitely recommended. I don't have any experience with 5/16" tubing, and hope I never do, but I would hope the loop lengths are 150' or less. I also hope that the 0010 Taco Primary circ is pumping the opposite direction. And, the boiler piping could well be piped for better flow efficiency.

Tekmar 018 4-way & 011 motor actuator is a nice combination, but I would have used VSIM.

REgards, Jed

hr

A couple primary loop ideas

Either of these would allow the boilers to operate by themself without flow through the unfired one.

No doubt firing both at once is causing the short cycling. bad for the boilers, flue, and fuel bill

A ROUGH guess of 4000 sq feet times 20 BTU/ sq. ft.= 80,000 load for the house. This could be on the high side, with a tight house and some basement zones. You may need to fire only one boiler to meet the heat and DHW load??

The second would only fire for snowmelt or rapid DHW recovery.

Regardless the tekmar boiler stage control would sort this out.

Consider what is going on when only one or two zones is calling that 0011 on! Thinks are moving pretty fast no doubt. Hense the need for a properly sized and adjusted bypass valve.

I'd be tempted to split the zones to at least two pumps. Maybe seperate the 5/16" zones to one pump and the others to a lower head pump.

Wonder how close all the required water supply temperatures are?

If there is a design this should be noted. Add all the required temperatures up, divide by the number of zones to get your average required water temperature. If they all fall within 10° of that average, then one mix station would work. I'd still supply the highest temperatures ones first off the mix valve.

Flow setters may be needed to get all the zones the required gpm.

hot rod

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Weezbo

looks like it to me.

boilers have thier own secondary tie ins to primary loop.this allows equal run rotation or,lag and lead orsimultaneous operation of both boilers.

Mark Eatherton1

AND..

the boilers are not losing heat up the flue or to the room when they're not "on line"..

ME

Constantin

Thank you, Thank you, THANK YOU!

Guys, you are the best. A big group hug all around, there is now lots for me to do and think about.

For one, I am going to take a closer look at Vitodens and Munchkin literature to see what could be done with a system that is allowed to condense. In an all-radiant house, with a propane fuel source, and a motivated HO, this payback will probably be short enough to satisfy everyone.

Next, a closer look at what the system does vs. what it ought to do. I happen to think that a constant circulation system will keep the house much happier than the bouncing 4-way valve that is currently cycling back and forth as the 011 fires and then shuts down.

I was thinking something like 3-4 circulators for the house zones that have a PAB each. That would require a bit of research to figure out what zones to group, but roughly the system would consist of zones organized by house sector/distance to manifold. Naturally, in an ideal world each zone would have its own pump running at variable-speed to keep up with the heat loss in each heating zone.

Bob Forand

It's in the zonevalves

Carl PE

Sorry, I got here late.

a couple assorted comments.

Like everybody else, I'm not too crazy about the 7-zone-valves-on-one-pump idea.

I also agree that each boiler should have it's own circ. You can't control your setpoint without it.

The 4-way valve is ok, but you'll have to run a higher temp in the primary loop to mix down to the secondary. This is going to ding your efficiency a bit.

Also wondering about the snow melt/utility room arrangement. If you've got the snow melt pump running, you're going to be dumping some really cold water back into the return. The boilers will like that, but the utility room might not.

Constantin

So, how about this?

Enclosed you will see a system that pretty much encompasses all the comments to date. Multiple circulators, PAB's, putting the boilers on their own circs, etc.

Naturally, this is a system which is almost so different from the initial one, that we may as well start over and install a Munchkin. But I digress.

Also note how I put the (presently disabled) snowmelt on the same circuit as the basement tubing. Since the basement is kept quite cool, I think they'll all play nice with each other.

Otherwise, the areas are pretty much split according to the surface area in each zone. I assume that a circ feeding a 3 story system will be reasonably happy for the most part. However, a 007 may be optimistic. In fact, none of the circs posted here have been researched - I first have to find out the loads on each manifold.

Note how the 4-way valve is no longer fed by closely-spaced T's but is part of the primary circuit. Also, the fan coil in the utility room (tiny!) is now fed by a smaller circulator than is presently the case.

So what do you think?

Constantin

And now the same with a Munchkin M199

With the Vision 1 + 2, it is my impression that I could suggest something as simple as the enclosed. Is that true?

One could add a TRV to the primary loop past the fancoil and IDWH to ensure that the radiant circuits never see high temps. However, the vision control logic appears to take care of the different water temps in the primary vs. the secondary loops by never allowing the two to come on at the same time.

Constantin

Thanks Carl!

I appreciate your help. The reason that the system as installed has a 4-way valve is that the boilers are non-condensing propane units. Thus, they have to be protected.

However, I still don't understand why Tekmar only shows the 4-way valve connected to primary loops via take-offs. The only good answer I can think of is that they are trying to prevent undue pressure loss if the 4-way valve body is significantly smaller than the primary manifold.

What was striking to me with the present system is the degree to which the 4-way valve gets excercised all the time and how the supply temps are on the order of 110°F all the time. Considering that it wasn't a design day, etc. the temp didn't make much sense.

Another issue with the system as installed is the super-high temperature inside the boiler room at any given time. The room only measures 5x10' with the boilers stacked on top of each other. It is perhaps not too surprising that the 7-zone manifold is installed on the ceiling!

The room is filled with combustion air via two forced blowers which activate whenever the boilers are firing. I happen to think a condensing, sealed combustion appliance would dump much less heat into the room because the supply temps are lower from the get-go, etc.

Considering the extant investment in Tekmar controls, I suppose they could go for the interface board and drive the Munchkin w/o the benefits of the vision controls. Naturally, spendier options like the Vitodens series are further options. It depends on what the owner wants to do, I'm just here to help advise.

Weezbo

*~/:) uhm...it looks better sorta....

right now though i'd just like to change your focus for a momment,being an engineer you have all kinds of information at your disposal,and having an adventurist spirit you have undertaken quite the project in your home. you remember a year or so ago when i asked if anyone had heard of some products and at that time i tested the waters with "Space conditioning"just to see where i had arrived...? well, you have a snow melt system are you say considering using it at all in the long light and summer, for heating?......... i notice you have a bit of ground work to still do outside,.....have you considered using the opportunity ? (some coils underground) (reverse heat pump type notion) it might not be absolutely the best cooling system available in the sence that it works within certain boundaries ..........energy wise however the comfort level both environmental and finacial should ameliorate any brief soirees outside of those boundaries. I hate to feel If Only....and i am...... you understand the principles involved move the heat to the cold, shed the heat from here to there,mix the water temps down and circulate them constantly slow down flows and increase flows with variable speed controller,with a slightly different lash up i can see it working .currently i am not liking the idea of placement of certain articles in the system as you have it modified .

Constantin

Hold on Weezbo! :-)

This is not for my house in Cambridge. This is a residence in Maine that I happend to visit this weekend where the owner complained about very high fuel expenses, expansion/contraction noises, etc. I volunteered to have a look, did some sketching, followed by a post here.

My Vitola and so on are staying right where they are. As for a GSHP, I considered it right up to the point where my calls/e-mails were not being responded to by the NE representative to ECR. At ISH, I found a company that actually does the installing and they were very eager. However, by then we already had conventional HSX-19's on order, so I dropped the matter.

Anyway, I am also considering Grundfos super brutes for this job since the three speed settings give some leeway re: proper pressure/flow in each circuit.

I would love to hear your thoughts re: these sketches since that's all they are, straw-men to burn, tires, to kick, etc. until the time comes this summer to find a contractor and make some changes.

hr

I like the second approch better

Not clear why you would want the 4 way in the primary loop. As it starts modulating it will change the flow in the primary loop. Possibly enough to bother the boiler requirements.

By using the closely spaced P/S tees you uncouple the high temperature and mixed systems hydraulicly. Flow in one does not effect flow in the other with P/S piping.

Still if major changes are in order AND the system, for the most part, operates in condensing temperature range, (the heatloss calc and system design should spell out this) then condensing, modulating, dhw priority equipped heat generators make a lot more sense.

And the fuel efficiencies are being proven over and over here, by those crunching the numbers on their own personal installs.

hot rod

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Carl PE_2

You're welcome.

"the boilers are non-condensing"

I completely missed that part. Pay no attention to my comment about efficiency.

I'm still somewhat puzzled as to why they used a 4-way valve for temperature mixing. Usually a 4-way is just used for reversing the flow, like in a heat pump. Sometimes you see them used in hot water systems that have long loops and/or big dT's to even out the slab temperature. I mostly just use a 3-way for the boiler protection/warm-up loop.

One other thing I'm curious about- in Hot Rod's sketch, each boiler has it's own p/s connection (multiple primary loops), rather than supply and return headers off the tees. Is there an advantage to piping it this way?

Wayco Wayne_2

Hey Constantin

I like the second as well. It may behoove you to split the load between several Munchkins so you can modulate lower on low load conditions. The vision 2 works with mixing valves. This would help you go to a constant circ design that you instinctively (and correctly) thought would be better. BTW I like your pictures. What do you use to draw them so nice and neat?

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Constantin

4-ways have many uses...

... for example, on my home heating system, there is a 4-way valve to mix down the water temp just in case the boiler is still hot from heating the IDWH to 140°F. Were it not for IDWH, my Vitola would be perfectly happy to be attached directly to a radiant floor system...

Usually, 4-way valves are used to protect the boiler from low-return temperatures, which would cause condensation. This seems to be the case with the Maine house I am describing above. On the other hand, in my own home, the 4-way valve exists to protect the radiant floor system from excessive boiler supply water temperatures.

Big-bore, motorized 4-way valves seem to be another Europeanism that may or may not find acceptance over here. They are quite spendy, and US pump producers like Taco seem to prefer 3-pump VS injection systems for some reason. :-) However, with the i-Series of smart motorized 3-way valves even Taco is starting to approach mixing water from a new direction. I happen to prefer 4-way and 3- motorized mixing valves simply because they accomplish the same task as VS mixing with a whole lot less energy.

In my own home, a 2" dia 4-way valve does the job and is part of the primary loop. In the Maine house, the 4-way is quite a bit smaller than the primary loop (1.5" vs. 3"). I will have to check flow rates and all that, but I doubt that anything bigger than a 2" manifold will be required in the Maine house. It's all just a matter of sending all them BTU's on a merry-go round in Siegenthalers Design Studio...

As for hot rod's sketch, I believe the idea is to isolate the boilers, yet to guarantee flow whenever one of them is firing. However, as I am a mere mortal among the gods of hydronics here, I wouldn't mind at all to be corrected! :-)

Constantin

Thanks Hot Rod and Wayne!

Your comments are just the kind of inspiration I am looking for. Enclosed is a sketch showing a whole lot of motorized 3-way valves incorporated into the previous design, something like the iSeries from Taco. This is one way to eliminate zone valves... :P

In fact, it comes dangerously close to a FHV-valve setup like Mike T has in his home (or was considering for his home). The FHV valves would have been a neat retrofit option if opening the walls was OK. Plus, the HO seems to like the Tekmar temp controllers. :-)

As for the pictures, I use Concept Draw, a package I bought when I no longer had access to a Windoze machine to run Visio. Initially, I used it to sketch out my mothers boat electrics, down to all the connections on the Diesel Engine. Makes trouble-shooting a whole lot easier... 20"x30" drawing... wheee.

After sketching a heating system proposal, I paste the drawing into Graphic Converter, where I turn the image from Bitmap into RGB, followed by a downsizing to 500-700 pixels across, followed by a save to GIF. The end result is a pretty small image that seems to do the trick... never have had the straw-men burned quicker or more brightly!

As always, further comments would delight me.

Constantin

Or... holy pumps, Batman!

A similar idea to constant circulation above, but with just one TRV to prevent all-too hot water from entering the radiant system. After that, VS pumps regulate just how many BTU's reach each zone. Overall, I suspect that this approach should work just as well as the previous one, but with a lot more electrical consumption. OTOH, this approach may be preferable, since the space constraints make installing a lot of pipe very tricky.

This is one way to ensure that each zone is constantly circulated at a optimum temperature? Oh the places you will go...

One other general comment: I have yet to perform a heat loss calculation. However, I doubt that the house is consuming all that much heat, considering the vintage of the windows, Corbond in the walls, etc. With the new Dungs valve, a M140 might modulate adeqately to preclude the need for multiple boilers, yet heat the house and (perhaps more importantly) the IDWH to satisfaction.

A heatloss will tell that story. The only tricky room that I found was one with a glass and french-door wall on two sides. This room also features a stone floor, but I wonder if on a windy day there isn't enough infiltration to make life rather interesting. Conditions when we were up there were rather balmy (never below 0°F) so design-day performance is something I couldn't assess.

hr

The snowmelt load

should be very easy to calculate, measure the square footage and assign 100 - 150 BTU/ square foot. The exisiting piping and loops will limit what you can actually send to it.

A copper tube boiler is not a bad match for snowmelt. It sees a constant load, inexpensive, easy to plumb, and could possibly use the current flue. This would eliminate a HX or having to glycol the entire loop.

It may put you into just one condensor for the building and DHW load.

hot rod

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Constantin

Ah yes, the snow melt load...

Well, unlike most snow-melt projects you guys undertake, this one is pretty tiny. The snow-melt was installed in a 3'-wide strip of concrete that runs the length of the building outside the rear entrance/twin garage doors.

The total outside area is < 100 ft², and presently that load isn't even connected to the heating system. Presumably, they discovered that the snowmelt was probably not needed, as long as the 6" thick basement slab was continuous from indoors to outdoors. Heat transfer anyone? :-)

But even if the snowmelt were to be re-activated, the total load would be less than 15,000 BTU's by your worst-case calculation. I suspected a low load myself, hence the position of the snowmelt in the "radiant section", when most people attach them directly to a primary loop.

Once I have a heat loss done, I'll have a much better idea of how much heat the house + snowmelt actually needs. So far, I'm betting on less than 150kBTU input, which is where I'd like to see the boiler for IDWH heating (50 Gallon buderus with 4 full (low-flow) bathrooms attached to it).

hydronicsmike

Constantin,

why don't you call me at 250-545-7749, Ext. 214 and we can discuss what you have.

I see a couple of things in the original install. First, the 371 does not stage multiple boilers, it only runs a single one. So I dont know how they are staged right now.

The Mixing Valve is piped in the right fashion, but as Hot Rod stated, the Tee's could be closer together. You don't need a Pump feeding the Mixing Valve, as the Pump on the System side would pull any required heat through the Valve and out of the closely spaced tees.

Anyways, if you want more of my input, give me a call. Thanks and Happy New Year to you.

Mike

jerry scharf_2

cheap sensors and custom controls

Constantin,

Too bad you aren't closer to the victim. If you were, I could help you cook up a system similar to the one I'm designing. The pump does constant delta P, and globe valves vary the flow to each radiant loop. Sensors are Maxim 1-wire 12 bit units at about $4 each. Globe valves are ~$60 each, and the control point input and output is about $75.

Simplest control is a highly damped goal seaking PID. Next is an a PID that learns "normal" case and adjusts the PID constants to better track the goal. Next level is varying goals with the weather. Finally comes adaptive predictive controls based on a near critical damped attack curve.

Oh what fun!

On second thought, wait till I have lived with it a year or two.

jerry

Constantin

The funny thing is...

... back when I took controls, robotics, etc. classes I wondered why these simple algorithms weren't used more in heating systems and other aspects of our lives. Granted, stepping out from classical control theory to state-space can be a bit daunting, but it shouldn't be holding people back as much as it is. Simulink, etc. were developed for a reason...

Anyway, what do you think of my proposal simply using variable-speed circulators? I should be able to achieve most of the objectives stated in your solution (constant circulation, comfort, etc.) assuming that a Tekmar, Vitotronic, or Vision, etc. system can send proportional VDC signals (and incorporate PID controllers).

On the other hand, perhaps Taco has value-priced these units? I don't want to discuss actual prices, but it would be good to know at what rough multiple the VS series is sold at relative to a regular 00-series circulator, vs. what iSeries 3-way mixing valves go for.

Anyway, I suppose I could always take Tufts up on its offer to further educate me (1 course/semester is free, IIRC). On the other hand, I already have a day job, a house renovation, etc. :-)