Want to optimize my radiant heat system so it works like it should

rongill

Hello all,

Pics attached
The house is 3 floors ~ 1800 SF on each floor.
10 heating zones (50% are in use)
Viessmann vt-100 boiler
Separate DHWT
Taco 5r-503 controller
Taco 007 circulating pumps
Pics attached
No outdoor reset
No floor sensors
Initial water temp for floors - 126F
Weather here in the winter (25F - 50F)
Loop sizes (Most are around 220 with a couple around 280)

The reason I'm wanting to make adjustments was when we have our thermostat set at 74 the system heats up tiles are warm and when the thermostat is satisfied the system is off for many hours causing the floors to be cold. This is a constant cycle and it is uncomfortable.

What I have done is lowered the water temp to 105F and adjusted the thermostat up so the system is always running and this seems to keep the floors comfortable (not hot by any means)

The other adjustment is the flow rate (allen key knob). These are now approximately set to 70% open.

- What are everyone's suggestions to keeping comfortable floor temps?
- What are the downsides to having the zones constantly on
- Where should I keep the flow rate adjustment at (there is no reading)

Any other suggestions?

Gordy

Let's start with the misconception radiant floors are always warm. The only time they are consistently warm is with high loads. That is not efficient, and that is how they were when structures were poorly insulate, and fuel was cheap.

Neutral should be the goal. Neither warm, or cold to the foot.

If you think about it. If a floor is constantly 77* that temp is noticeably warm in my opinion. If that floor temp is constantly at that level the room will overheat, unless you like a 75* room temp. Unless that room is very high load that sheds the btus that a,floor of that temp produces.

To gain highest efficiency your missing some important features. ODR, and constant circulation.

rongill

What is the best way to achieve constant circulation with what I have.

Gordy

I'm not a viessmann guru. Maybe @Chris will be along here to help you out.

I do know that the addition of ODR will make a world of difference.

rongill

I agree with the odr - not sure how much work it is to do after the fact. For now just trying to get the system to work it's best with what I have.

When I had 126 temps going in the system the thermostat was set at 72.5 and would be satisfied after a few hours and heat may not get called for another 12 hours which would cause the floors to be noticeably cold.

Paul Pollets

This system should have hydraulic separation (low loss header) and constant circulation. The 1" header may also be too small to service 10 zone valves. The boiler cannot be installed without HS if the flow rate exceeds 6gpm. The Vitodens 100 is not set up for constant circulation, the 200 model is. An aftermarket control (Tekmar) could be added to provide constant circulation, but now the cost is way more than the 200 would have been.

rongill

can anyone give me an estimated ballpark on how much it would cost to convert?

If I choose to not convert because of costs - what can I do to make my current system perform better.

Paul Pollets

Pricing is not discussed on this site (per the owner) You'll have to find a local contractor who is familiar with Tekmar controls and repipe and rewire the existing boiler or convert to the Vitodens 200 with low loss header.

CMadatMe

Yea as Paul pointed out the boiler should have the low loss header. But he also has the wrong boiler pump. Taco 007-IFC isn't helping him out either. He'd might be moving 4gpm across the HX.

Here's the fix...

1. Put in the correct Boiler Pump
2. Install the Outdoor Sensor
3. Install the Low Loss Header
4. Stop with the micro zones.
5. Vitodens 100 has 0-10VDC - Use it.
6. Follow Paul's instructions and find a local contractor

I'm still wondering what that aquastat is for. Guessing the radiants high limit.

2nd Fix....

1. Put in correct Boiler Pump
2. Install the Outdoor Sensor
3. Install the Low Loss Header
4. Stop with the Micro Zones
5. If micro zoning, scratch #3 install Buffer Tank
6. Remove Aquastat
7. Install Taco I-Valve and use that to run the radiant on its outdoor sensor if you aren't installing the Viessmann Sensor. If you do use the Viessmann sensor, scratch I-Valve and install a Thermostatic Mixing Valve. Get the boiler on it's proper heating curve.
8. Follow Paul's instructions and find a local contractor.

rongill

chris - thanks for the comments - when you say I might be moving 4gpm - should I be moving less or more? as I have an adjustment knob for each loop on the return.

I will be bringing someone in locally to review and revamp the system - eventually.

CMadatMe

You should have the proper boiler pump as stated in the installation manual - Either a Grundfoss UPS-15-58 or Taco 0015 (previously 00R).

You aren't pipe correctly either. You're going to kill that boiler. Think of it like this. Go outside and take 10PSI out of all your tires on your vehicle and drive around until you need new ones. How long do you think that will take? Would you get the same gas mileage? Let's me save you a little time. You'd need tires rather quickly and your gas mileage will plummet.

Same thing here. Your efficiency is gone and you'll break down sooner rather then later.

Car tires and gas mileage people understand. It's my new analogy for explaining in layman terms. Easy to get the point across. The car still works, runs and so doesn't your boiler but now weigh out the long term damage and extra $$ you have to spend.

rongill

that is not good - man I thought the guy we hired knew what he was doing. He is viessman certified but I guess that doesn't mean much.

CMadatMe

Not is all lost. Boiler should be piped like page 21.

http://www.viessmann.ca/content/dam/vi-brands/CA/pdfs/wall-mount/combiplus_tdm.pdf

I misread your original post. Though the entire project was 1800 sqft. Its 5,400 sqft!

Really need to get that piping and boiler pump straightened out. You'll never get the full load out of the boiler even on your DHW Call. Your system side flow rate will easily exceed the max flow rate of 6.2gpm across the HX. You're limping on half the system and no way a floor should stay off for that long.

What's the radiant application? That little Vitodens is heating the entire house? No other heat?

Who did the radiant heat loss and design? Did you ever get it from the installer? You paid for it, it's yours...

rongill

chris - appreciate your time - for my own knowledge -how should I be piped vs what I have now?

rongill

did not get any heat loss calcs from the contractor / pretty sure it didn't happen .

yes the vitodens 100 heats the entire house

when I click on your link I get a permission denied... also the link was for the combiplus version which I dont have ..

here is the link - http://www.viessmann.ca/content/dam/vi-brands/CA/pdfs/doc/cpk/vitodens_100-wb1bc_is.pdf/_jcr_content/renditions/original.media_file.inline.file/vitodens_100-wb1bc_is.pdf

CMadatMe

Page 21 of the manual I posted. That's how the boiler side and indirect should be piped. The radiant well that's different. There are many ways. I see what he did. He's using the Aquastat as a high limit. In other words, if the water temp gets too hot, the Aquastat is going to shut down power to the radiant system circulator so you don't cook the floors when all he had to do was pipe the boiler correctly, install the outdoor sensor, set the correct heating curve and install a thermostatic mixing valve for the radiant system.

CMadatMe

Doesnt' matter combi plus version or older WB1B. Same thing.. Page 41 of the link you posted works.

CMadatMe

All he had to do was add the PC600 Card to the Zone Control Plug in Port and bring that back to DHW in the boilers power pump module. No need for that aquastat.

http://www.taco-hvac.com/uploads/FileLibrary/102-094.pdf

Willing to bet that's why your radiant floor is off for hours. Because you aren't pipe right and wrong boiler pump. DHW takes forever to satisfy or its continually coming on.

What is the heating dial # set to?

This is why that aquastat is there on that radiant header.

Note 1-
Optional high limit safety control of heating circuit E.
[During DHW production with DHW terminal activated,
the boiler supply temperature will be set automatically
to 172ºF (78ºC)].
The heating system must be protected from excessive
temperature if no automatic mixing valves are used or
no DHW priority is required.
After the DHW call for heat is satisfied, there is a 20
second pump post-purge time.

Not only this but because he's not using the outdoor sensor, the boiler is going to ride to a setpoint. As an example. The dot is 140 degrees. What's the aquastat set for?

Setting the dial between 1 and 6 will provide a set-point
value of 81ºF to 178ºF (27ºC to 81ºC) respectively. The
dot between 4 and 5 represents the factory default setpoint
value of 140ºF (60ºC).

rongill

the dhwt is priority 3 on the taco sr531 - it seems to call the boiler atlesst once every 45 minutes.

the dial set point seems to make no difference / I set it at 1 or 6 - it seems the aquastat is overriding it. The aquastat was set at 126 - I lowered to 120

Paul Pollets

Not every contractor knows Viessmann, (or other boilers as well). That a Vitodens 100 was selected for a 5000sf home tells a lot. The ability to follow the manuals and install the piping and pumps correctly is not easy. There is a shortage of highly trained hydronic mechanics in this country. That is sad. Your system can be fixed, if Chris' info is followed.

CMadatMe

No don't lower it!!! It's keeping your radiant off in conjunction with the DHW priority. Boiler can't satisfy it, always runs, so Radiant zones off. Then the aquastat keeps it off until it doesn't see a water temp higher then the 120! What # on the dial is the boiler set to? The dial on the right at the boiler.

You don't understand. Because the outdoor sensor is not hooked up the boiler is riding to a set point/target temp. Once that water temp gets above that aquastat setting, no more radiant..

rongill

it is set to the default setting between 4 and 5. Chris the dial on the right seems to have no effect on the boiler temp. There is a separate thermostat before the piping that goes into the zones that controls the temp. .. this was set to 126 .. I'll post Pics.

Are we saying the boiler or oversized or undersized?

rongill

zone 1 is heating and zone 3 is dhwt

rongill

chris - the dhwt seems to get satisfied after 6 minutes. - when the the thermostat calls for heat the radiant heat is running. The issue I seem to have is at this incoming water temp of 126 the thermostat gets satisfied petty quick and doesn't call for heat for hours.

I understand the overall goes is to bring someone in to do a revamp.

For instance if I lower that incoming temp to 110 and have my thermostat set at 72 the thermostat will never get satisfied and the radiant constantly runs with the boiler cycling every 15 minutes.

CMadatMe

That gray box is is not a thermostat it's an aquastat!

The dial on the left with the little spout on it at the boiler, does absolutely nothing as it pertains to the boiler set point. That one on the right has everything to do with boiler setpoint. It's on the dot - The boiler is targeting 140 degrees.

That thing you are calling a thermostat. See what it's doing is shutting down the radiant once the temp gets above that 120 degrees you set. So your boiler is giving you nothing and thus why the radiant is off FOR HOURS!!! Well, its really not off. You just aren't getting any run time. Get rid of the aquastat it's doing nothing but not allowing your radiant to come on and the cause of your initial post.

I'll go back to my initial post..

1. Install Outdoor Sensor
2. Install Correct Boiler Pump
3. Install Low Loss Header
4. Throw that Aquastat in the Garbage
5. Add a Thermostatic Mixing Valve for the Radiant
6. Change the TASR503 to the New SR503-4. The new version provides 2 end switches. One is a DHW Priority End Switch. The normal end switch will go back to RT on the Boilers Control. The Priority End Switch will go to DHW. Bam, done, simple. I'm telling you to change the relay because you may not find the PC600. Taco basically has put its feature integral to their current control.
7. Pray you have enough boiler to satisfy your DHW and Heating needs once you get the other half of your project done..

Dropped Mic, I'm out. Time for Bill Maher.....

rongill

got it .. and sorry for the confusion as you can tell this is not my field ... thanks for all your help and will get someone to look into it.

rongill

when the temp goes below the aquastat the boiler cycles and heats water 12degreef higher than what is set at the aquastat.

CMadatMe

No problem. Once you get that heating curve set, the thermostatic valve I'm tell you to install will act as a high limit but when the heating curve wants to give you a lower water temp, it will just go wide open, I call it a low budget modulating mixing valve. Boiler really is the mixing valve but the thermostatic protects the floors..

rongill

Chris said:

No problem. Once you get that heating curve set, the thermostatic valve I'm tell you to install will act as a high limit but when the heating curve wants to give you a lower water temp, it will just go wide open, I call it a low budget modulating mixing valve. Boiler really is the mixing valve but the thermostatic protects the floors..

Chris do you have any experience with honeywell's wireless odr
http://www.alpinehomeair.com/related/W8735EInstallation.pdf

Will it work with my boiler?

Fred

@rongill , I Maybe sticking my nose in where it doesn't belong but that Honeywell ODR says it connects with an aquastat. I thought Chris told you to throw the aquastat in the garbage?

CMadatMe

No the Honeywell Outdoor Reset will only work with products in their Red Link Line. As an example, conventional boilers come with honeywell aquastats that will work with this but you can't use it on a condensing boiler unless, its a Burnham Alpine but Burnham has their own with their name on it..

CMadatMe

Just dawned on me. You're zoned Zone Valves and the guy used a Circulator Relay... SMH.....

What he did was pigtail the zone valve end switches to the TT on the SR Relay to run that Radiant Pump and Wired in the Indirect Pump to the priority side. You only have 2 pumps from what I can see so #2 or #1 on the relay should be empty. Could you take the cover off that relay and post a pic of the wiring please.

I want you to disconnect the aquastat but want to see that wiring first before I tell you how to fix this without spending a dime..

rongill

Chris - not home today but what I know is zone 3(priority) is the dhwt and zone 1 is heating ... nothing on zone 2

rongill

there are 3 pumps - 1 heating, 1 dhwt, 1 on the retien

CMadatMe

Boiler pump is controlled by the boiler. I'm curious to know how he got the boiler to go into high fire for DHW call. Would like you to flip the control down on the boiler then unscrew the cover on the square box (Power Pump Module) looking straight at you. It has 4 spring loaded screws so only a few turns, they don't come out. Take a pic and post.