Contractor left this - converting from baseboard to in-floor radiant loop.

JordanHershel

We’re renovating our kitchen and wanted to switch to radiant in-floor heating in order to free up some wall space that was previously used for baseboards. We had an HVAC contractor come out and disconnect the old heat runs and they left some stubs for me to hook into for the radiant loop. Everything copper is existing/what the contractors left us with. 





The one thing that’s really got me hung up is the mono flow tees - are they going to divert too much water and overpower the mixing valve? If they are, would the easiest solution be to use a 4-way mixing valve instead or should I repipe this to just use standard tees that are closer together?



General questions I think I have a handle on, but would appreciate some pro opinions on:



-I’m currently planning on using an electronically controlled mixing valve. Is this overkill in this application? My thinking is that it will close when heat isn’t needed and keep the floor temp from creeping up. With just a circulator on the relay though, would that even be an issue?



-Since we only have one loop for the radiant floor (~200ft long) when I did calculations for flow rate I got something much smaller than what I’m seeing from most hydronic circulators (1/3 GPM, maybe 2ft of head loss before factoring in connectors). I know oversizing by a lot isn’t great but I’m also seeing circulators rated with a range (0-12gpm, 0-12 ft head). Not sure if I should find a really small circulator or if any would work as long as it’s not undersized or horrendously oversized. 



Appreciate any help!

STEVEusaPA

What happened to the contractor?

EBEBRATT-Ed

@JordanHershel

It's not that simple. You just cannot connect radiant to a high temperature baseboard system. You need a mixing valve and a lot of other hardware, Do some research,

Caleffi has good hydronic designs in there IDRONICs that you can download and read (at least how to hook things up but not a complete tubing design)

Steamhead

Looks like you need a different contractor.

EdTheHeaterMan

JordanHershel said:

[Edited for clarity]
We’re renovating our kitchen and wanted to switch to radiant in-floor heating in order to free up some wall space that was previously used for baseboards. We had an HVAC contractor come out and disconnect the old heat runs and they left some stubs (Stub A & Stub B) for me to hook into for the radiant loop. Everything copper is existing/what the contractors left us with. 






The one thing that’s really got me hung up is the mono flow tees - are they going to divert too much water and overpower the mixing valve? If they are, would the easiest solution be to use a 4-way mixing valve instead or should I repipe this to just use standard tees that are closer together?



General questions I think I have a handle on, but would appreciate some pro opinions on:



-I’m currently planning on using an electronically controlled mixing valve. Is this overkill in this application? My thinking is that it will close when heat isn’t needed and keep the floor temp from creeping up. With just a circulator on the relay though, would that even be an issue?



-Since we only have one loop for the radiant floor (~200ft long) when I did calculations for flow rate I got something much smaller than what I’m seeing from most hydronic circulators (1/3 GPM, maybe 2ft of head loss before factoring in connectors). I know oversizing by a lot isn’t great but I’m also seeing circulators rated with a range (0-12gpm, 0-12 ft head). Not sure if I should find a really small circulator or if any would work as long as it’s not undersized or horrendously oversized. 



Appreciate any help!

I'm not seeing the problems that the others (@STEVEusaPA, @EBEBRATT-Ed & @Steamhead) are concerned with. If I'm correct, you hired a pro to get you ready to ReDo the kitchen. The contractor did his job and valved off the "NEW" piping that include a mixing valve, circulator for the radiant loop and a diagram for this to work. You are correct in believing that you do not need Mono-Flo Tees. But as long as they are no causing problems with the other emitters in the system You do not need to change them out.. The "Power" or force created by the Mono-Flo tees will not push more heat into the low temperature floor loop. This assumes that the stubs you are referring to are where I indicated them on your drawing.

But I might be mistaken and this is more representative of what the contractor did.
The additional portions of your original diagram are the proposed system design. If this is more accurate, then for such a small radiant section, I would use an inexpensive pump equal to the Taco 007, or B&G or Wilo or Grundfos and a standard low temperature mixing valve that you set and forget. Don't over design something that can be so simple.

EdTheHeaterMan

EBEBRATT-Ed said:

@JordanHershel

It's not that simple. You just cannot connect radiant to a high temperature baseboard system. You need a mixing valve and a lot of other hardware, Do some research,

Caleffi has good hydronic designs in there IDRONICs that you can download and read (at least how to hook things up but not a complete tubing design)

There is mixing valve in the drawing. But the proposed valve is electrically controlled. for such a small job I would use something like AM-101-US. or AM-101C US

Agree that IDRONICs is a good resource

JordanHershel

EdTheHeaterMan said:

I'm not seeing the problems that the others (@STEVEusaPA, @EBEBRATT-Ed & @Steamhead) are concerned with. If I'm correct, you hired a pro to get you ready to ReDo the kitchen. The contractor did his job and valved off the "NEW" piping that include a mixing valve, circulator for the radiant loop and a diagram for this to work. You are correct in believing that you do not need Mono-Flo Tees. But as long as they are no causing problems with the other emitters in the system You do not need to change them out.. The "Power" or force created by the Mono-Flo tees will not push more heat into the low temperature floor loop. This assumes that the stubs you are referring to are where I indicated them on your drawing.

But I might be mistaken and this is more representative of what the contractor did.
The additional portions of your original diagram are the proposed system design. If this is more accurate, then for such a small radiant section, I would use an inexpensive pump equal to the Taco 007, or B&G or Wilo or Grundfos and a standard low temperature mixing valve that you set and forget. Don't over design something that can be so simple.

Yeah, I was wondering what the other guys were talking about. I'm a DIYer and potentially out of my depth, but I've spent some time looking into this and didn't think I was that far off haha.

What the contractors did is closer to your second image. They valved off just after the monoflow tees - basically cut out the baseboard and capped it in the basement below. The only additional thing they did in this part of the house was to add the ball valves and stub out about 6in. Everything else in the design I came up with, which is why I wanted to run it by some pros.

Good to know the monoflow won't divert enough water to force open the mixing valve. Sounds like I can just get a more basic one and a smaller pump. I was looking at a Taco 007 or grundfos already so I'm glad I was on the right track.

Appreciate the advice!

mattmia2

What is the loop that this is tying in to, is it a series loop or is it monoflow or what?

JordanHershel

mattmia2 said:

What is the loop that this is tying in to, is it a series loop or is it monoflow or what?

I think monoflow - not sure on the terminology. Everywhere else in the house we have baseboard heaters that have monflo tees coming off of a central line from the boiler. The returns from the baseboards feed back into that central line. Basically like this image I found except we have monoflow tees on the supply and return of each baseboard.

Ironman

The problem that I’m seeing is that first of all a heat loss calculation should have been done to determine if a radiant floor would supply sufficient heat at design temperature.

Second, the radiant needs to be connected directly back to the boiler and not be dependent upon the baseboard loop and its thermostat. A radiant floor has a different dynamic than BBs and should be piped, pumped and controlled separately.

hot_rod

I’m not sure you can cut into a mono flow system like that without changing the hydraulics on the balance of the loop

mattmia2

monoflow is B&G's trademark for their diverter tee system but it also has been genericized to any diverter tee system. You get more flow in an emitter with 2 diverter tees vs one diverter tee and one regular tee.

EdTheHeaterMan

Ironman said:

The problem that I’m seeing is that first of all a heat loss calculation should have been done to determine if a radiant floor would supply sufficient heat at design temperature.



Second, the radiant needs to be connected directly back to the boiler and not be dependent upon the baseboard loop and its thermostat. A radiant floor has a different dynamic than BBs and should be piped, pumped and controlled separately.

I agree with the need for a load calculation. However what is the alternative if there is insufficient floor space to heat the kitchen? No heat at all? In my opinion, that is not a good alternative. Besides, I like stepping on a warm floor in my bare feet in the morning when I get my first cup of coffee

Disagree about a home run to the boiler room. The water temperature in that section of the 1" main is only going to drop a few degrees (depending on how many baseboard loop takeoffs are between the boiler and the disconnected kitchen takeoff). How the lower temperature for the floor loop is achieved is the question. The Query here is what mixing device and circulator do you use. I believe that on such a small project, the simpler the better. A Taco 007 will draw enough heated water and enough cooler recirculated water thru the mixing valve to maintain a sufficiently warm floor for most of the heating season.

Not contesting @Ironman's suggestion to be piped back to the boiler room is not a better design because the 1" loop will only be charged with heat when there is a call for heat for the high temperature baseboards. But as the outdoor temperature is cooler that will happen more often. To better regulate the high temp on time, some of the baseboard's dampers can be adjusted partially close.

If the homeowner finds that on extreme cold outdoor conditions the room is unacceptably cold, then additional emitters can be considered at that time. Adding a Kick-space heater under a cabinet will do nicely as long at you somehow design a control system to give the floor heat priority, and only supplement when needed.

Just the opinion of someone who has already done this exact job. But what do I know? BTW no kick-space heat was ever needed for that particular customer.

EdTheHeaterMan

hot_rod said:

I’m not sure you can cut into a mono flow system like that without changing the hydraulics on the balance of the loop

I bow to your experience Bob, but I don't think there will be any difference since this is not a "Cut In" but the removal of a section of baseboard the was already there.

Tinman

I wouldn’t sign off on that. Why reinvent the wheel when you know it’s going to roll? If you want a low temperature radiant zone added to your high temperature hydronic heating system, add a tee on the return and the supply near your boiler, throw in the new circ and mixing valve and you’re good to go. More Frankenstein systems aren’t needed. 

And like most others have said, if you don’t know how much heat you’re losing how will you know how much to add - tube spacing, floor R-values, supply water temperatures. They all matter. 

pedmec

yeah, i can see a problem with the main circulator causing flow thru the radiant system. whats stopping the flow thru the radiant loop when the main monoflo loop is calling for heat?

Ironman

pedmec said:

yeah, i can see a problem with the main circulator causing flow thru the radiant system. whats stopping the flow thru the radiant loop when the main monoflo loop is calling for heat?

I think it may be the opposite: why would water flow through 200 - 300’ of 1/2” pex tubing when it can find an easier path through the cone of a Monoflo tee?

Nothing is gonna flow through the floor tubing unless it’s on a separate circulator.

JordanHershel

Appreciate all the different perspectives on this! I get having the thermostat call for heat from the boiler separate from the baseboard loop would be ideal, but especially since this is a DIY and a few people have told me it'll be good enough I'll give this a shot. Worst case I just have to change the piping in the basement and maybe have a pro come back out to do a better primary/secondary system at the boiler. (I think I'm using those terms half correctly ha).

I agree with a lot of the sentiments on here - wish the contractor had educated us a little bit, but that might also partially be on me. He came in to do the estimate and we were already set on in floor - had already bought the tubing and fins to DIY haha. He probably figured that was a losing battle and/or that it would bruise my ego to try to tell me it wouldn't work. He did insist that we make sure the walls were insulated, which they are. I ended up doing a heat loss calculation after the fact and we should be golden with the loop I have planned, assuming the floor works on the baseboard loop. The kitchen is also fairly open to an adjoining room that also has plenty of baseboard heat so I'm assuming any shortfalls will mostly balance out.

As long as the mixing valve doesn't get overpowered by the main circulator in the primary loop I'm thinking we're going to move ahead with the knowledge that I might have to invest a little more if it doesn't end up working as well as we would like. I'm obviously the novice here, but like @EdTheHeaterMan is saying, I've seen this exact setup in a few books that I got when reading up on the subject. I think the worst case is it might end up feeling a little chilly vs anything catastrophic. It's a 1950's house with a fair bit left to update after the kitchen remodel so as long as it keeps the room above 60 on the coldest day in the winter I'm fine with having to revisit/supplement later.

EdTheHeaterMan

@Steve Minnich I like to ask the question "Did the heat in the kitchen work before you removed the radiator? Was it too hot or too cold?" The answer will let you know if the removed baseboard was the correct size. (or too big or too small). Remember this kitchen has a track record. There is a known value that is being removed. X number of feet of baseboard x BTU/Ft. value of that baseboard = the required value of the replacement heat emitter. There is no reason to get any more complicated that that. Since Load calculations are very easy to do today, I might double check the numbers and when they both are close to the same requirement, then I believe there is no question in my mind. But to tell the OP he is going about this project all wrong is in my opinion a disservice to the homeowner.

This guy is doing the research and wants to know if it will work for him. Not what you would design for a McMansion in the Hamptons a new construction complete design and build of a 20,000 sq foot mansion in your neighborhood type project

@JordanHershel let us know how it works out next December.

Also if you need that kick-space heater in the future, know that it can be taken off the same stub A & B that the low temperature loop is on.

Yes, I know, that the kick-space heater will be heated when ever the house thermostat is calling for heat... But you have to ask, How much of that that will actually go into the room if the fan is off? Not too much!
And so the water returning to the main 1" loop from that emitter will probably be only one or two degrees lower than the inlet water temperature.

Tinman

EdTheHeaterMan said:

@Steve Minnich I like to ask the question "Did the heat in the kitchen work before you removed the radiator? Was it too hot or too cold?" The answer will let you know if the removed baseboard was the correct size. (or too big or too small). Remember this kitchen has a track record. There is a known value that is being removed. X number of feet of baseboard x BTU/Ft. value of that baseboard = the required value of the replacement heat emitter. There is no reason to get any more complicated that that. Since Load calculations are very easy to do today, I might double check the numbers and when they both are close to the same requirement, then I believe there is no question in my mind. But to tell the OP he is going about this project all wrong is in my opinion a disservice to the homeowner.

This guy is doing the research and wants to know if it will work for him. Not what you would design for a McMansion in the Hamptons

@JordanHershel let us know how it works out next December.

Also if you need that kick-space heater in the future, know that it can be taken off the same stub A & B that the low temperature loop is on.



Yes, I know, that the kick-space heater will be heated when ever the house thermostat is calling for heat... But you have to ask, How much of that that will actually go into the room if the fan is off? Not too much!
And so the water returning to the main 1" loop from that emitter will probably be only one or two degrees lower than the inlet water temperature.

Why would the quality of design be dependent on what your zip code is? Attacking a project with a commonly accepted practice doesn't necessarily equate to greater expense. Please tell me what is so difficult about piping in two tees near the boiler versus creating a hybrid distribution off of the often temperamental monoflo system?
Heat loss is different than knowing a previous length of baseboard heated the room. My experience with baseboard is that it's usually installed wall to wall, grossly oversizing. Where's the logic in using that approach? And like you said, load calcs aren't hard nor is the math that follows.
Radiant panels in kitchens are different because if the room is 200sf doesn't mean you 200sf to work with. By the time you deduct the lower cabinets, appliances, and the island you're left with a fraction of that area to work with.
Someone else mentioned Siggy advocating for this. I may have missed that, but I've never seen it. The only thing I've seen that was close is having a panel rad off of two monoflo tees with a very small loop of suspended joist heating on the same piping loop (not supported by John either).
We just have different opinions on this. That's ok.
I'll continue with the approach that I'll do the work on the front end to make sure everything is working by the time I get to the back end.

EdTheHeaterMan

@Steve Minnich The "quality of the design" is not dependent on the zip code. I was referring to the size of the project. I'm pretty sure that there are very few 2 bedroom ranch homes worth $80,000 in the Hamptons or on Philadelphia's Main Line, or on Kiawah Island near Charleston SC. But there are plenty of homes that are all 7 figure and 8 figure properties. I'm thinking that none of them are installing one DIY 200 ft loop of radiant floor heating, to see if it might be good enough to work in the rest of the house maybe.. But for clarity, and so you don't miss my point and go off on a tangent that makes no sense, I will remove the Hamptons reference from my previous post.

My direct question to you is "What exactly is the engineering principal or exact calculation that you can site that would explain exactly why tho OP's idea will not work?" Have you done the math for his project and or completed a similar job that has had such catastrophic results that you must do everything your power dissuade this DIY from his ultimate demise.

Remember Steve, we all do not have your unlimited resources to do the project your way. Some of us are just getting by since the current administration has made so many improvements to the economy. LOL

Just asking for a friend.

Tinman

Ed - I’m not trying to convince the OP of anything. He has already made his decision.

No, I have not done any math whatsoever on this nor will I. I assume you haven’t either. I’m knee deep in work that doesn’t allow for that. I apologize if my opposing point of view offended you. 

EdTheHeaterMan

Steve, I have done this exact job during my varied career in the industry. So when someone proclaims that something that I know will work "will not work or should be done differently" then I like to make sure the the OP knows that is an opinion AND NOT A FACT

To quote your previous post "I wouldn’t sign off on that. Why reinvent the wheel when you know it’s going to roll? If you want a low temperature radiant zone added to your high temperature hydronic heating system, add a tee on the return and the supply near your boiler, throw in the new circ and mixing valve and you’re good to go. More Frankenstein systems aren’t needed. .

This tells me that you have not done, what I know from experience, does work.

And I'm not offended. I believe you know what you are doing and admire the fact that you come here to share your expertise and experience. I just want the DIY and novice Pros, to know what does and does not work and help them to understand that some opinions are opinions and some posts are fact.

I don't mean to offend you either Steve. I'm just a little over passionate. Maybe

pedmec

Ironman said:

pedmec said:

yeah, i can see a problem with the main circulator causing flow thru the radiant system. whats stopping the flow thru the radiant loop when the main monoflo loop is calling for heat?

I think it may be the opposite: why would water flow through 200 - 300’ of 1/2” pex tubing when it can find an easier path through the cone of a Monoflo tee?

Nothing is gonna flow through the floor tubing unless it’s on a separate circulator.

well considering that there is two monoflo tees on that main line and it looks like a pretty decent amount of separation? i thinks that's a pretty good pressure drop between the tee's. and the main circulator has to move water, its just a matter of where it's going to go.

Tinman

EdTheHeaterMan said:

Steve, I have done this exact job during my varied career in the industry. So when someone proclaims that something that I know will work "will not work or should be done differently" then I like to make sure the the OP knows that is an opinion AND NOT A FACT

To quote your previous post "I wouldn’t sign off on that. Why reinvent the wheel when you know it’s going to roll? If you want a low temperature radiant zone added to your high temperature hydronic heating system, add a tee on the return and the supply near your boiler, throw in the new circ and mixing valve and you’re good to go. More Frankenstein systems aren’t needed. .

This tells me that you have not done, what I know from experience, does work.

And I'm not offended. I believe you know what you are doing and admire the fact that you come here to share your expertise and experience. I just want the DIY and novice Pros, to know what does and does not work and help them to understand that some opinions are opinions and some posts are fact.

I don't mean to offend you either Steve. I'm just a little over passionate. Maybe

We could go on all day like this.

I know guys...
that still charge ACs by the "beer can cold" method.
that still use rules of thumb like 50 BTU/h/sf for heating.
that still use 600 sf per ton of AC.
that use water heaters as boilers.
that size boiler piping based on the inlet and outlet sizes of the boilers.
that have used a myriad of P/S piping that is completely wrong.
that pump directly toward the PONPC.

Most of this will "work" to some degree and each of those statements are facts and ZERO of these methods are the correct way to do it.

EdTheHeaterMan

@Steve Minnich said: "Most of this will "work" to some degree and each of those statements are facts and ZERO of these methods are the correct way to do it."

@EdTheHeaterMan Agrees.
The Beer Can Cold method is OK but I prefer a glass of red wine at room temperature

see how i did that, took the conversation to drinking which was far from your point. kind'a like the zip code thing you did... LOL

Tinman

I’m an ice-cold Pepsi kinda guy. 

mattmia2

I thought there was a circulator in the added loop itself. I'll go with it could work or it could be the only thing in the house that heats, you wouldn't know without some fairly complicated math.

Tinman

Just another observation - in P/S piping using closely spaced tees, the tees are kept close to minimize pressure drop between them so the pumps involved will have negligible affect on each other. 

In this situation, you have tees that are at least the width of a radiator apart and one tee, sometimes both tees, with Venturi cones in them. Between the length of pipe and a Venturi tee, there’s going to be considerable pressure drop. 

I don’t see how the boiler circ and the ad-hoc circ don’t influence each other. At the least, it seems you’ll have two circs in series with one another increasing the flow through the radiant loop and it’s mixing valve slightly while increasing head significantly.
If I have that right, that doesn’t sound like a sound hydronic principle unless that’s your goal which I’m certain it isn’t.  

hot_rod

there are quite a few steps involved in properly designing a diverter tee system, I think 11 steps detailed in Modern Hydronics. A lot of attention to pressure drop and how small changes in piping, mis-piping or modifying them can throw them for a loop. So teeing into them loop via any means will have an effect. Certainly flows change when the radiant kicks in with another circulator involved.
I don't have any first hand experience, but I have read and understand the hydraulic logic behind them

pecmsg

EdTheHeaterMan said:

@Steve Minnich The "quality of the design" is not dependent on the zip code. I was referring to the size of the project. I'm pretty sure that there are very few 2 bedroom ranch homes worth $80,000 in the Hamptons

I can guarantee NONE!

Medium price is $750,000.00

Add 2 zeros to that and your a little closer!

HomerJSmith

I didn't delve into this post, thoroughly. Remember, stand alone mixing valves require a temperature differential to regulate properly. I like the Taco I-Series mixing valve which is sensor regulated. Also, I use a balancing valve to regulate the flow thru the pex loop.
And... pump away from the mixing valve.

How much heat energy you are going to get out of the pex loop for a given length is determined by the flow and the water temperature.