Hydronic Radiant Heat System Question

[yeldogt]

Not all boilers are combi boilers .... in fact most are not. That is just what you are running across. You don't want one of the premade panels. The second panel is static .... you pick the output temp. That's not what you want.

Take my advise and spend 1/2 hour and look over the Viessmann 200 install manual -- see how easy the piping can be. That type of boiler can do true outdoor reset with duel curves .... it can even do a second one with a mixing valve.

Did not the person who plotted out the piping work off of a load .... he must have done it based on something.

You have 5k of parts with just the boiler and panel. Better to have the right boiler .. a nice LLH .. and the correct pump. Add the spirovent and expansion tank. The zone controls are a different matter ... it's had to tell how you want to do it. Putting thermostats and valves on the zones can get expensive .. that's why I used the Cross Manifolds. Pay once upfront

 

[yeldogt]

If you look at this set up .... see the black rectangle ? That the LLH ... it has a loop and pump to the boiler on the left for the "primary" and a pump out to the system. The "system" is 4 manifolds. 2x 8's, 1x6 and 1x11 ..... so 33 loops of Pex running off of one system pump -- the "secondary". The whole thing is 3 pumps with the 3rd pump feeding the white tank (indirect domestic hot water)

If you look off to the right of the LLH you see the boiler water feed/ Spirovent and expansion tank. KISS ... rules.

This is a very tight space -- some of the black pipe is the propane header coming in from outside feeding the dryer /stove/ boiler/ and secondary furnance that I installed in the ducted system w/ AC.

You can see two of the Cross manifolds on the left .... the other two are remote about 40" away. all running from that one Alpha II pump in the middle

It's also hard to see but there is a sensor at the LLH that the boiler uses to monitor the water temp in the header .... this is the true temp in a Primary/ Secondary. The outlet temp of the boiler is not the temp of the water going to the radiation as it gets mixed.

 

[kj_mustang]

Bosch has the Greenstar boiler that comes in Heat only and combo models. I have the heat only 100 model installed in my new home about 5 years ago. Heats the radiant and an external domestic hot water tank.

 

[fitter30]

I don't plan to use the DWH part of the combi-boiler but it seems like every boiler I find is a combi-boiler so I figured I'd just get one of those and not use the DWH part. If I could find a heat-only boiler I'd be all for it. I know I want condensing and something efficient, all those seem to be combi-boilers.

I see your point on the basement. I suppose something 100K or less would be fine. Is there a boiler that you recommend?

If I supply too hot of water to the basement will it just overheat the space? Wouldn't the zone just run for shorter periods if it had the hotter water? Would you recommend making my secondary loop similar to this pre-made panel that mixes the return water with the supply water for one of the zones?

thermostat that use a floor sensor plus room temp.

 

[fitter30]

One pump for 33 loops with muilti zones good luck with that. They make straight boilers lockinvar is just one of many.

 

[premis]

If you look at this set up .... see the black rectangle ? That the LLH ... it has a loop and pump to the boiler on the left for the "primary" and a pump out to the system. The "system" is 4 manifolds. 2x 8's, 1x6 and 1x11 ..... so 33 loops of Pex running off of one system pump -- the "secondary". The whole thing is 3 pumps with the 3rd pump feeding the white tank (indirect domestic hot water)

If you look off to the right of the LLH you see the boiler water feed/ Spirovent and expansion tank. KISS ... rules.

This is a very tight space -- some of the black pipe is the propane header coming in from outside feeding the dryer /stove/ boiler/ and secondary furnance that I installed in the ducted system w/ AC.

You can see two of the Cross manifolds on the left .... the other two are remote about 40" away. all running from that one Alpha II pump in the middle

It's also hard to see but there is a sensor at the LLH that the boiler uses to monitor the water temp in the header .... this is the true temp in a Primary/ Secondary. The outlet temp of the boiler is not the temp of the water going to the radiation as it gets mixed.

I appreciate all the help, and I have no doubt that the way you are telling me to do it is the best way. But, it's over my head and removes the ability for me to DIY this. I'm going to look for a smaller boiler, probably something 100-120K BTU and I'm going to put a mixing valve on to feed my basement zone so I can reduce that water temp, if needed. I'm going to design my primary and secondary loops similar to the pre-made panels I linked to. Those are sold by a major retailer (Menards), I'd imagine they have to work well.

Thanks again for all the help!

 

[PoorUB]

I would skip the mixing valve and just run a pump for each zone, tee'd off the main boiler loop.

 

[premis]

I would skip the mixing valve and just run a pump for each zone, tee'd off the main boiler loop.

I'm going to do a pump for each zone. I think I'll add a mixing valve but use valves to isolate it if I don't need it. Just how this panel is done. That way it's there if I want it but I can bypass it if I don't.

https://www.menards.com/main/plumbing/hydronic-radiant-heat/radiant-heat-control-panels/hydro-smart-trade-2-temp-3-zone-zoning-panel/hs2t3zmp/p-1444433736037-c-8521.htm?tid=-6285746348620573519&ipos=13

 

[PoorUB]

Again, if you run a pump for each zone there is no need for the mixing valve. It is just one more point of failure. Plus that panel you show is really for high temp baseboard and and floor heat on the same system running high boiler temps. Not what you are doing. Just buy a simple three zone panel. https://www.menards.com/main/plumbi...84-c-8521.htm?tid=4377881163126690349&ipos=12

Hey, but what do I know, I just installed and serviced HVAC , including floor heat for many years!

 

[premis]

Again, if you run a pump for each zone there is no need for the mixing valve. It is just one more point of failure. Plus that panel you show is really for high temp baseboard and and floor heat on the same system running high boiler temps. Not what you are doing. Just buy a simple three zone panel. https://www.menards.com/main/plumbi...84-c-8521.htm?tid=4377881163126690349&ipos=12

Hey, but what do I know, I just installed and serviced HVAC , including floor heat for many years!

Ok, I trust you. I'll skip the mixing valve.

My garages (2 zones, one 420 sq ft and one 1800 sq ft) are just bare concrete. But the basement zone (1905 sq ft) is going to be mostly carpet but also a tile bathroom and an exercise room with a rubber floor. Knowing that, is still ok to just use the same water temp in all of those? Any tips on what water temp to use? I was thinking 110-115 degrees(F)

 

[PoorUB]

Your water temp will probably never need to be over 120F. Your 110-115F is probably right on. What would you do with the mixing valve? Run one zone at 110 and the other 115? See what I am getting at? 5-10 degrees difference in water temp won't make any difference if you run a thermostat and pump for each zone. The floor will get only as hot as it needs to to satisfy the heat load. The water might be 120F but the floor maybe only 75-85F.

 

[premis]

Your water temp will probably never need to be over 120F. Your 110-115F is probably right on. What would you do with the mixing valve? Run one zone at 110 and the other 115? See what I am getting at? 5-10 degrees difference in water temp won't make any difference if you run a thermostat and pump for each zone. The floor will get only as hot as it needs to to satisfy the heat load. The water might be 120F but the floor maybe only 75-85F.

Thanks, @PoorUB! I appreciate the help. I'll skip the mixing valve.

Believe it or not, I've installed about a dozen of these systems, I was the HVAC "*****" while I was in High School and College (20 years ago). And I helped my dad install the system in his 1,000 sq ft shop. But I've never had to deal with designing the system. I built a nice house, so I don't want a janky system. But, I also don't need the best of the best.

I appreciate all the feedback from everyone. I've always loved this forum!

 

[yeldogt]

You should not need a static mixing valve and as Premis and I have stated the panels are incorrect for your application ... you want to follow piping in the manual for the boiler that is picked.

I'm trying to make what you are doing less complex with fewer pumps and related equipment ... that's why I directed you to looking over a manual.

 

[yeldogt]

Your water temp will probably never need to be over 120F. Your 110-115F is probably right on. What would you do with the mixing valve? Run one zone at 110 and the other 115? See what I am getting at? 5-10 degrees difference in water temp won't make any difference if you run a thermostat and pump for each zone. The floor will get only as hot as it needs to to satisfy the heat load. The water might be 120F but the floor maybe only 75-85F.

It is an older way of doing the systems .... it uses all high wattage pumps for zone control for full manifolds. The temps are higher .... need pump control.

My boiler in that situation is rarely making over 105 degree water and mixing it in the 95 range ... all running at around 40 watts max.

 

[PoorUB]

It is an older way of doing the systems .... it uses all high wattage pumps for zone control for full manifolds. The temps are higher .... need pump control.

My boiler in that situation is rarely making over 105 degree water and mixing it in the 95 range ... all running at around 40 watts max.

Well, I do agree with your post #18, but I think it makes the OP's head explode!

 

[Firebrick43]

Again, if you run a pump for each zone there is no need for the mixing valve. It is just one more point of failure. Plus that panel you show is really for high temp baseboard and and floor heat on the same system running high boiler temps. Not what you are doing. Just buy a simple three zone panel. https://www.menards.com/main/plumbi...84-c-8521.htm?tid=4377881163126690349&ipos=12

Hey, but what do I know, I just installed and serviced HVAC , including floor heat for many years!

And the pumps are not?

If you run one vfd pump, a mixing valve, and zone valves things are much more efficient and the zone valves can be manually manipulated if need be. A system can run on one pump and no controller if necessary by manipulating the mixing valve.

Pump zone systems were king for years because how much pressure could vary with a valve zone system, but with VFD pumps that is in the past.

 

[yeldogt]

Well, I do agree with your post #18, but I think it makes the OP's head explode!

I get it .... I'm not the best "teacher" . That's why I said for the OP to look at that Viessmann manual ..... they have colored diagrams and it's actually easier to understand the whole thing when you see the pictures.

The OP has a boiler cost pushing 3k (and not using the DHW) .... I have bought Viessmann boilers w/ all the sensors for less than that. Same with the panel -- he has linked to $1500 panels. Think I paid $400 for that Viessmann LLH -- the pumps, boiler feed and all the piping would cost under $1500. The venting can add up depending on how complex. Using a LLH makes all the piping simple -- it becomes like an erector set.

I wanted to explain a bit more -- the OP clearly spent some $$ on setting up the Pex. Someone must have done calculations and when doing a residence the desire for tighter temp control is more important vs doing a garage.

In a garage at 64 degree target -- if it drops a bit or overheats past 65 it's not a big problem.

 

[PoorUB]

And the pumps are not?

If you run one vfd pump, a mixing valve, and zone valves things are much more efficient and the zone valves can be manually manipulated if need be. A system can run on one pump and no controller if necessary by manipulating the mixing valve.

Pump zone systems were king for years because how much pressure could vary with a valve zone system, but with VFD pumps that is in the past.

Sure, but he was looking at a panel with three zone pumps and a mixing valve. He didn't need the mixing valve.
I would probably would go with a single pump and zone valves if it were my system, just not the crappy Honeywell zone valves that have been sold for decades.

 

[Firebrick43]

Sure, but he was looking at a panel with three zone pumps and a mixing valve. He didn't need the mixing valve.
I would probably would go with a single pump and zone valves if it were my system, just not the crappy Honeywell zone valves that have been sold for decades.

agree on the honeywell. I use caleffi valves/controller and grundfos pumps

 

[PoorUB]

agree on the honeywell. I use caleffi valves/controller and grundfos pumps

The Callefi valves are great. Sold hundreds of them and not one warranty.