HELP WITH VIEGA RADIANT

GaryT

I built a new house a few years back and installed a staple up climatrak viega radiant system with basic heating control, outdoor sensor, indoor sensor and 2 brass manifolds in parallel - each with 4 loops (approx 365 Ft. each) of half inch O2 barrier viega pex and a viega injection station with 3 speed grundfos circulator. R30 insulation and a 1.5 inch hot pocket and radiant barrier under the climatrak. No issues making target temp on the coldest days so far BUT the floor takes a long time to reload and there is some temp fluctuation waiting for reload. Research tells me that an injection station should never have been used for this system as the install calls for a mixing station only. So, I plan to replace it ASAP. Viega offers a basic mixing station and an enhanced mixing station with ECM circulator and options for fixed - constant pressure - and auto adapt functions. Viega also offers an "all in one hydronic mixing block" which replaces the basic heating control but still utilizes the outdoor and indoor sensors. Does anyone have comments or experience or advice with the basic mixing station vs. enhanced station vs. hydronic block. I'm usually not a fan of "all in one " systems. Just want to get it right for this upgrade. Thanks in advance for your comments. GaryT

TAG

My plate systems always use constant circulation .... when you say "reload" are they going on and off?

The plate systems are going to take longer to heat the finished floor -- the Pex has to heat the plate and then the plate has to heat though the sub and finished floor. It's not going to happen quickly -- that's why you need constant circulation with a low watt pump.

Also -- I was told with plates you want the insulation up against the floor and plates ...no air gap. The plate heats the floor directly. That may slow down your system as well if you are now heating the air gap

hot_rod

Not sure what you mean by reload?

Are you trying to setback temperatures in the rooms? Radiant systems do take some time to respond, best to find a comfortable temperature and let it run.

OR is the boiler cycling on and off?

Rich_49

Did you mean you have an 1 1/2" air space below the Climate Track and tubing ? If yes , why ? Insulation should be right up tight since this system is more about conduction . The air space should be used on suspended tube , Ultra Fin type applications only .

psb75

Your loops are just over 20% too long. That hinders the overall system performance. 5 loops would have been much better. That would have left each loop just under the widely recommended less-than 300' per loop. So, the reduction of the insulation air-gap can only help. ANY set-backs are not recommended during heating season.

GaryT

The house comes up to set temp and then the basic heating control lowers the target temp of the circulating water - the rooms start to cool off and the room temp drops a few degrees before the reloading can warm the floor again. Floor is tile over hardie backer and 3/4 plywood. R value is very low - lower than hardwood. The circulator runs constantly except in WWSD. Sometimes solar heat gain causes an issue on a very sunny winter day. But that is rare. I do know that initial loading takes time- I am OK with that but I never thought I would see a noticeable drop in room temp before set room temp is re-gained. Research tells me that the fault may have to do with the injection station which is specifically not recommended for a staple up system - Viega's manual state to only use a mixing station with climatetrak. The boiler always makes 180 degree water and the injection station only allows the right amount of hot water to mix-in that the basic heating control calls for. The boiler is a cold start Viessman boiler ( not sure about high mass or low mass) but the indirect water heater actually acts as a low limit so between the call for heat and hot water the boiler does run a fair amount. Thanks

Rich_49

psb75 said:

Your loops are just over 20% too long. That hinders the overall system performance. 5 loops would have been much better. That would have left each loop just under the widely recommended less-than 300' per loop. So, the reduction of the insulation air-gap can only help. ANY set-backs are not recommended during heating season.

It very well could be that someone actually performed some math and these lengths are fine . Manufacturers SUGGESTED / Recommended maximum loop lengths are just that . One may also do the math based on their specific install to determine what lengths the circuits may be .

TAG

I'm confused -- you are using both staple up and Climatetrak to describe what has been installed. What one do you have ? Climatetrak is not staple up.

True staple up does have the gap and needs much hotter water ...

In any case you need to lower the water temp and see if you can hold the temp in the room w/o I guess is a room thermostat. Sun gain can be an issue but I have found that one needs a floor thermostat in those situations to keep the floor at a minimum temp when the room reached temp. Otherwise when the room cools low enough to restart the flow to the floor -- the floor is too far behind.

GaryT

Thanks everyone who chimed in so far. The air gap is dead space (sheet rock underneath) and insulated at the rim so the air gap is proper. I have added a radiant reflective barrier reflecting up to the sub floor thus creating the air gap and the batt insulation below that reflective barrier far exceeds the recommended R value. Also, the longest loop is 365 the shortest is 325 - with the majority just above that. Those lengths were approved by the Viega rep who designed it. The floor of the great room shoots (laser) an even temp across over 40 feet. and the kitchen, den, hallways and baths all read just about the same. That would not be the case if loop length is an issue. Also, when I shoot the individual return pex going into the return manifold they all read about the same temp - lower than the supply of course but close enough to each other. The system can keep the 22 x 42 great room over a 4 car garage at 68 degrees when its below zero outside. The tile is an upscale 20 x 20 porcelain. FYI

Zman

Injection mixing works just fine for radiant. It was popular in the '90s before smart mixing valves became commonplace.
Injection mixing can sometimes be "surgy" if the pipes are not sized carefully. Contractors often oversize the injection loop which causes them to have trouble maintaining a consistent temperature.
Your radiant loops are longer than many, with correctly sized circulators, it is probably workable.
Got pictures?

hot_rod

What type of thermostats? They can have a few degree differential. The temperature will vary some on the reading. With some stats you can adjust that hysteresis. 

European stats often don’t have temperature read outs, set them until you are comfortable. They didn’t sell well in the US😉

GaryT

Thank you guys. To Zman - there is only 1 circulator - its on the injection station - 3 speed Grundfos - manifolds are run in parallel - only 2 manifolds. The head distance from circulator to climate trak system is about 4 feet. Someone said that maybe the water is travelling too fast to shed heat efficiently? I have the speed set to the middle position of 3 positions. To TAG. I never thought to lower water temp- the mix max on the basic heating control is set to 135 - never really goes above 124 on the coldest days and that is rare . TO EVERYONE - I only have a room sensor not a Tstat- So when I want to change the room target temp I do it via the basic heating control settings. I have a full hydo air - one zone- backup that I use in the first chilly days of fall but come Thanksgiving time I drain and winterize the hydo system and set the radiant to one temp and it stays that temp until May 1st. This wqy no one can play around with the radiant system - Like Ron Popiel - "just set it and forget it". Also, this system is not plumbed primary secondary but most other tradesmen tell me that's not an issue - just may take a bit longer to pull hot water maybe only seconds. The injection station and first manifold is only 5 feet from the boiler - 2nd manifold is another 30 feet away and fostapex runs from the first to the second manifold. Keep the comments coming and please add if anyone has experience with the basic mixing station vs. the enhanced mixing station with ECM circulator vs. the newer "all in one" hydronic mixing block. Thanks

GaryT

ECM Circulator settings!! So I installed the enhanced mixing station about a month ago and ir replaced the older injection station. The ECM circulator has 7 settings - 3 Fixed speed, 3 Constant pressure and an AUTO (factory) setting. i was told to leave it on AUTO as it will somehow learn the system. For the first few days with warm outside temps the wattage used read about 12 watts and the GPM read about 2-3 gallons per minute. Now the AUTO setting stays on 43 watts (almost the max of 45 watts) and the GPM always reads 6 - despite the fact that the basic heating control is not calling for any heat - in fact the target temp is lower than the actual temp. I thought that the basic heating control was supposed to shut off the circulator when no call for heat is present - but the circulator runs constantly even though there is no call for hotter water. It only shuts down during WWSD (warm weather shut down) which is set at 70 degrees F. So I feel like the AUTO setting is not the best. Can anyone give some advice as to whether I should try one of the fixed speed settings or one of the constant pressure settings on the ECM circulator. It just seems to me that running at almost full capacity (wattage) and at 6 GPM all the time seems excessive even though the basic heating control is not calling for hotter water. Thanks in advance for any input.