In-Floor Hydronic Radiant Heating Issues - New (to us) House with Oil Boiler

MasterC

This looks like a great place frequented by a lot of knowledgeable folks. I'm hoping you will be so kind as to help me solve a problem or two that we are having with our heating system. We purchased this house just over a year ago (December 2015). It has a radiant heating setup that (I think) may have been put together in a somewhat atypical manner. I have a shared album with pictures of the setup here. We are experiencing a couple of issues and numerous questions.

My most obvious problems in a nutshell:

• Some heating zones are not functioning properly.
  
• Zone 6 (top pump in the setup) does not appear to circulate hot water. After running for a while, the pump will feel hot to the touch, along with the first several inches of the copper pipe coming out of the pump, but the rest of the pipe never gets hot.
  
• Zone 4 circulates hot water if it is there, but hot water does not get there if it is the only zone calling for heat. It can run all night with the thermostat set for 70 degrees (or whatever) and the room temp at, say, 60 degrees, and if it is the only zone calling for heat during that time, the tubes never heat up, even though water is circulating. If other zones are calling for heat and circulating, hot water circulates through all zones (including Zone 4) and the tubes heat up.
  
• Zone 4 is my most urgent problem, as this is the heat for our master bedroom. Zone 6 heats rooms that are seldom utilized.
  

Some quick and perhaps relevant facts that I know:

• House was built and system installed in 2004/2005.
  
• House is 2 stories, plus basement. The boiler is in the basement.
  
• The boiler is fueled by home heating oil; it provides domestic hot water and radiant heat hot water.
  
• No heating issues were observed during the first winter when we moved in. It may have been working fine, or it may not have been as cold as this winter, and/or we had too much going on with settling in to pay close enough attention.
  
• The system has 6 independent zones, each fed by it's own circulation pump.
  
• Each zone has a RiteTemp thermostat (I think an 8022C) control
  
• Each thermostat is wired in through a SP-30 SetPoint Temperature Control.
  
• The interior walls of the house are insulated, so turning off certain zones and shutting doors to rooms that are not used appears to be pretty effective.
  
• The boiler heats the output water up to approximately 190 degrees F; it kicks on when that temperature drops to approximately 150 (although the temp is as low as 135 before it starts going up again) and kicks off when the temp is around 180 (but gauge continues drifting up to near 190).
  
• The pressure seems to be between roughly 11psi (lowest observed boiler temp) and 14psi (highest observed boiler temp).
  
• Each zone has multiple sub-loops that can be manually throttled or turned off using a quarter-turn valve.
  
• When water is circulating, moving the big lever on the 4-way-mixing-valve (?) changes the input loop temp dramatically...from no increase up to 170+. Except when only Zone 4 is circulating, then "turning up" the lever has little effect.
  
• Last spring, after shutting all thermostats off, I noticed the tubes in the top zones would be warm, even though no pumps were running. To solve this, I ended up shutting the valves before the pumps and the valve in the return line until we were ready to use heat again.
  
• Pictures show the setup in the boiler room from multiple angles, including the details of the boiler and closer pictures of some of the system components.
  

Please let me know if you have any thoughts on the system, or especially how to solve the stated problems. I also have some other questions about the system, but this post is long enough for now!

Thanks!

MasterC

In case it helps, here are the details of some experimentation I was trying to do the other day and some info I left out in the first post:

Zone 1 - basement
Zone 2 - 1st floor main living areas (primarily)
Zone 3 - upstairs bedrooms
Zone 4 - upstairs master bedroom
Zone 5 - upstairs bathrooms
Zone 6 - 1st floor side rooms (primarily)

Experiments:

Z4 and Z6 on only: loop not heating up (boiler temp 190, loop temp 85);

Z5 on also:, same results;

Z2 on also: loop temp comes up
to ~130, hot water felt in tubes of zones 2, 4, 5; not in 6 even though on. reminder note: 1 and 3 still off.
Timeline notes during this test state:
7:24 - burner kicked on, boiler temp down to ~130
7:36 - burner off, boiler temp up to ~190
7:42 - boiler on again when temp hit 150. Temp got as low as ~130 before started rising again.
7:50 - boiler off as temp crossed 180... Drifts up to around 190.
Loop temp swinging between around 120 and 140 as boiler temp goes up and down.
Z6 still on but cool, other on zones feel pretty warm. Z6 pump feels pretty hot (measured 132 with IR thermometer; other on pumps nearly as warm at 127), but copper pipe from Z6 pump only hot for first few inches. Other on zones hot across entire pipe.
7:56 - boiler temp 170, loop temp 136
7:58 - boiler temp 158, loop temp 132
7:58 - B150, L130 (B = boiler temp, L = loop temp)
8:00 - B145, L129
8:01 - B155, L130
8:05 - boiler off, B190

Turned down mixing valve
---Turned off Z2 heat. ---
8:23 - B188, L110

Turned up mixing valve, loop temp goes up

---Turned off Z5 heat, only Z4 on---
8:36 - B188, L100
Turned up mixing valve, loop temp does not go up!


--turn on Z1 --
(note: Z1 basement return water started super cold)
Loop temp now 80... Then drifted up to 90. Boiler kicked on.. Kicked off again at only 160 this time? Drifted up to B185+ though;
Loop temp now drifting up to 100;
Crank up mixer valve - loop temp drifting up to 120... But at this mixer setting with other pumps running, would have been way hot (cranked up to 8)... Wait, now it's drifted up to 140. Turned mixer back down, temp dropped to 120, 110, 100... Seemed steady. But then boiler kicked on, heated up to B190, loop temp was like 80, but now rising to 100....

Note: I can't tell if it was a little erratic at the end there with the addition of the cold basement loop water, or if I got something mixed up in my notes.

STEVEusaPA

You do know zone 6 valve is closed?
There is alot to digest here. Can you contact the previous owner to see if it ever worked.
There should be some design schematics.
My first thought is besides being kind of a mess is that it's piped wrong-way wrong. I think you're common piping needs to be bigger. And lot's of controls.
A proper design would consider (from a full heat loss) how many btu's, flow and head were needed for each zone.
In your case, it looks like there's just not enough btu's for zone 6.
I have a 6 zone system (4 radiant), and an indirect.
I made minor adjustments to water temp and flow until it was dialed in-fussed with it all winter (that's just me at my house)
Moving the mixing valve back and forth and looking for instant results isnt going to work.
I think you need to find a really good hydronics person, reverse engineer what's there, and compare it to a proper heat load. Then you will know if you can fix this with proper circs, some near boiler piping, or you need a total redo.
For starters, do you have enough water in the boiler/system? Is all the air purged.
Zone 6 could be a bad circ, a stuck flow check, or air bound

MasterC

Haha, yes, in some of the pictures the zone 6 valve is close. Good eye! I have often left it closed, since we don't normally heat that zone, and I have noticed when the heat is off that sometimes hot water circulates there even without the pump running. I recently discovered that the zone would not work when we had guests over the holidays and we tried to heat that zone. The valve was definitely open during that time and during my experiment the other day.

Thanks for checking though!

MasterC

Oh, you added more to your post. Thanks for your time!

I can contact the previous owner, but he will tell me everything always worked great. Says he talked to heating people and it's the most efficient thing they've ever heard of....

But yes, I believe zone 6 did work when we first moved in and I was checking everything out.

Zone 4...we didn't notice this problem specifically last year. But it's a tricky one to just notice, because it sometimes works, especially if other zones are on at the same time. Even last year I noticed that it would take a looong time (many hours) to go from like 62 degrees up to 68 degrees. I thought that was probably kind of normal for radiant, but I'm sure this issue doesn't help.

I did find some design info in paperwork left by the previous owner. I'll dig that up and post it later, but I don't know for sure whether it was right in the first place, or if it is accurate or not to what was actually installed.

And the mixing valve moving back-and-forth...that was just to record some observations. There were clear differences in the response between the "problem" zone and other zones, which is all I was really trying to see. Maybe it's not helpful, but I thought it showed something.

MasterC

For starters, do you have enough water in the boiler/system? Is all the air purged.

Forgot to address that. How can I tell? I was wondering about an air problem, but not sure how to identify that or fix it. Should there be bleed valves at the top of the loop somewhere?

Jamie Hall

These things tend to be complicated - but maybe that's just me; I'm just a poor steam guy. However. First thing that strikes me is that the loop temperatures may be higher than they need to be -- but that's for when we get all the loops working.

You have, I take it from your description, pumps on all 6 zones. There are control and isolation valves, but no zone valves -- at least that is what I think I see in the pictures.

Therefore, what should happen is that when a zone thermostat calls for heat, the pump should run. If the isolation valves are open, the piping beyond the pump should get hot quite quickly.

So... the very first thing to find out is if the pump for each zone is running when the thermostat is calling for heat. If not, that needs to be tracked down and checked. Unhappily, there are a number of possible reasons why a pump might not run.

This will take a really good look at the control wiring to troubleshoot; you have more than one problem...

MasterC

Therefore, what should happen is that when a zone thermostat calls for heat, the pump should run. If the isolation valves are open, the piping beyond the pump should get hot quite quickly.

Thanks - I believe that is happening for all the zones, with the noted exceptions:
-Zone 6, the pipe only gets hot for a few inches;
-Zone 4, the water circulates, but isn't really hot unless other zones are bringing water that's hot up from the mixer.

But this reminds me of a question I had - there is one other pump that I believe circulates water back to the boiler. It can be seen in some of the pictures on the wall to the left of the boiler. When should that pump be running? I had a theory that maybe it should be on when any one (or more) of the other pumps is running, but maybe that's not working for Zone 4.

Jamie Hall

Which is what I mean by having multiple control problems here. That boiler circulation pump should be running when any zone is calling.

Gordy

If piped P/S hard to tell from pics if it is, and done correctly. Thermostat calls for heat. Boiler loop circulator, and zone circulators engage. Boiler goes through its proving sequence, and fires 30 seconds give, or take. Then boiler has to get circulating water hot. Depending on convector types, and when the last call for heat was could take a bit before pipes are noticeably warm.

The boiler loop circulator should always run when any zone(s) call for heat.

MasterC

I know next to nothing about this, but from a bit of googling I don't think it is piped P/S. Simplistically, I think it is plumbed basically like this.
(Edit...well, there's more pipes going on that just that though. I'll try to sketch out a piping diagram.)

Which is what I mean by having multiple control problems here. That boiler circulation pump should be running when any zone is calling.

OK. I can try to troubleshoot why this isn't happening for Z4, assuming it's not. (It is hard to get back to that pump, so I haven't messed with it much yet.) But any pointers would be appreciated. What should be triggering this pump to turn on?

The thermostat wires all go to the SP-30 SetPoint Temperature Controls. I assume there are control wires from each of those to the corresponding zone pumps. But where would be the likely place that the logic from those is all tied together to control the boiler circulation pump?
(Edit: see my next post, but now I'm not sure it's intended to be tied in that way.)

MasterC

Edit - Update: Upon further inspection, I believe the circulation pump to the left of the boiler is for the domestic hot water supply. As I was down there trying to figure it out, the Taco SR501 relay light did kick on, which caused that pump to kick on. This was with no heat zones active. It circulated for a while, then the burner kicked on for a while, then it continued circulating for a bit longer after the burner went off. It is controlled by the thermostat sensing the hot water tank. I now believe this pump has nothing to do with the floor heating--it's just for the hot water.


Hmmm. After looking closer, I can't tell that the boiler circulation pump is ever running, no matter what. Looking at the wiring conduit, that pump is fed from this green Taco SR501 box. I don't think I have ever seen the "Zone 1" light on that box turn on. I just observed it through a couple cycles and tried turning various zone thermostats on or off (including all thermostats off), but it never changed. I also could observe no change on the pump.

That box is fed from this Safgard 550 Low Water Cut-Off box, and it's connected to a couple wires from this Honeywell box (temp sensor?). The Safgard 550 is connected to two other Honeywell boxes (this thing and this thing).

So, when I get a chance I'll start taking the covers off and probing around to see what's coming from where, and pulling manuals to try to see what these various boxes are supposed to do and piece together how this is all supposed to work. If someone already knows that information, any prompts to give a head start on that would be much appreciated.

Anyway, I now somewhat question the hypothesis that the problem with zone 4 has anything to do with the what I'm currently calling the "boiler circulation pump", since I couldn't tell anything different with it for any zone.

Paul Pollets

I'd install a motorized mixing valve and start over with a control that used outdoor reset and replace the pumps with zone valves and repipe the "near-boiler" piping. Tekmar makes a control that will do the job. Bad radiant is not easy (nor inexpensive) to fix and finding a local expert would help.

MasterC

Thanks Paul...I definitely have some questions related to doing much of what you said, and if it's worth it. But first I want to figure out what's going on and why it's not working as is.

I am sure Z6 used to get heat, and now it doesn't. I am fairly sure (but admittedly less than 100%) that Z4 used to get heat even when other zones weren't simultaneously calling for heat, but now it doesn't. I think I should be able to get those working as they were before without starting over. Then I'd love to discuss the merits of making those improvements.

Solid_Fuel_Man

Looks like zone 6 (top circulator) has the isolation valve closed. That's why no heat. Open it, there may be a leak for some reason it was closed.

Solid_Fuel_Man

I count 22 loops on what appears to be one three-quarter inch pipe that's a major bottleneck right there for flow.

Also the top circulator (zone 6) appears to have the isolator flange valve shut off that's why you're not getting any flow it may be off because there's a leak in that Zone.

Feeding the slab and all the other zones all the same temperature is also not a good thing to do. generally that will overheat the slab or under heat your other zones.

Taylor

MasterC

Thanks Solid_Fuel_Man. I am sorry for posting the pics with the Zone 6 isolation valve closed. That has misled several people, but I promise the zone does not work with that valve open either. Since we normally just shut off that part of the house anyway, I turn off the thermostat and sometimes shut the isolation valve as well. Otherwise sometimes hot water goes there when I don't want it to (a bit ironic, since I can't make it go there when I want to).

You are correct that I think there are 22 loops of 1/2" Pex tubing (in 6 zones) coming off of the 3/4" pipe. What size should the pipe be to feed all of that? Or, how many loops should the 3/4" pipe be able to support simultaneously?

I also appreciate the note about feeding the slab with the same temperature as the other zones. Sounds like something to try to fix in the future.

MasterC

I am not surprised to hear that there are a lot of sub-optimal things about this setup. However, I don't think any of those issues explain the current problems with Zone 4 and Zone 6. I would love to get thoughts on what my be the problem that developed there and how to troubleshoot it.

If it's a problem with air in the lines, how would I go about diagnosing and/or purging that?

Jamie Hall

Square one. Before you start worrying about air (you may well have to purge; that comes later) or excessive head loss (that could be a problem too) make sure that all the controls are actually doing what they are supposed to do and that the pumps are actually pumping or at least trying to. From your descriptions, I would guess that you have at least two control problems, and quite likely more, and possibly one or two pump problems. Troubleshoot and fix the control problems first, then any pump problems. Then you can go ahead an worry about the rest of the stuff.

Gordy

3/4" copper pipe has the ability to deliver 42,000 btus with in the industry standard of 2-4 fps flow rates.

With that being said if the 22 loops do not exceed 42000 btus when all loops are on (worst case).

hot_rod

Gosh, you could even push 6 gpm safely in 3/4 M copper, within that 5 FPS rule.

3/4 pex, around 4 1/5 gpm.
Although one pex manufacturer is promoting up to 8 FPS in pex. Maybe trying to close that copper pex gap

Gordy

Sure 6/22......

Solid_Fuel_Man

I guess I was just thinking even at 0.5gpm on each loop would be 11gpm..... I would have been much more comfortable with 1" copper for that many loops.

Notice I used decimals @Gordy

hot_rod

Solid_Fuel_Man said:

I guess I was just thinking even at 0.5gpm on each loop would be 11gpm..... I would have been much more comfortable with 1" copper for that many loops.



Notice I used decimals @Gordy

And it's possible that .6 gpm or more is required. The RPA suggests .6 gpm as max. for 1/2 pex.

Although with enough pump, I've seen 1 gpm stuffed into 300 foot 1/2 pex loops, about 10' head.

Certainly no harm in upsizing the trunk size, especially if flow required is unknown.

Jamie Hall

Seems to little inexperienced me (at least on hot water heat!) that a really significant advantage to upsizing the trunk size -- or any manifold, for that matter -- is that in doing so the head losses in the trunk become negligible -- which has to simplify things. Or so I would think...

JharrisSeattle

One important item you may want to look closely at is your radiant floor tubing. I could not help but notice the potable rated expansion tank on the system, seems odd due to the price difference and temp rating (lower) . Make sure the tubing that was insatalled is listed with an evoh barrier (oxygen barrier). I have seen plenty of systems over the years lose flow due to ferrous circulator volutes plugging up with rust due to large amounts of non oxy barrier tubing within the system. See if you can get a close up pic of the listing on the pex.

Gordy

I assume this is all radiant emitters?

Using the high end of 6 gpm. If all zones call at once just never know.

10* delta x 6gpm x 500= 30k
.27 gpm each loop avg.

15* delta x 6gpm x 500= 45k
.27gpm each loop avg.

20* delta x 6 gpm x 500= 60k
.27 gpm each loop avg.

With radiant floors 10* delta is a good design delta to use.

MasterC

Thanks for all the input.

I have added to the photo album pics of the markings on the PEX and the "Heating Calculations Worksheet."

The PEX seems to be marked with something close to:

"CPI DURA-B 1/2" (CTS-00) SDR-9 ASTM F-876/877 100 psi @ 180F Barrier DIN 4726 .070 12/06/01 A2X X11 006/FT"

Does the "barrier" in there mean it has the required oxygen barrier?


While I found the "design" information the previous owner left behind, I don't understand the heating calculations on it at all, and I have no real faith in their accuracy...and I'm reluctant to steer the conversation further in that direction before addressing the more immediate problems of zones not working right when they did before. But the worksheet I found seems to suggest flow rates as high as 4-4.5gpm for some zones, and as low as 0.75gpm to others. It seems to break down to 2/3 - 3/4gpm per 250' - 300' loop (as indicated on the worksheet, although the actual installed loops are different than the # indicated for some zones). Added all together, it's calling for 15.5gpm if all zones were on at once.

MasterC

Square one. Before you start worrying about air (you may well have to purge; that comes later) or excessive head loss (that could be a problem too) make sure that all the controls are actually doing what they are supposed to do and that the pumps are actually pumping or at least trying to. ... Troubleshoot and fix the control problems first, then any pump problems. Then you can go ahead an worry about the rest of the stuff.

So, I tested things out again, and I do not believe there is a control problem. I can turn on the thermostat to call for heat from Zone 6, and the Zone 6 pump (and only the Zone 6 pump) turns on. Same with Zone 5 thermostat and Zone 5 pump, and so on. All zone pumps turn on when their corresponding thermostat calls for heat. Also, there is no other loop circulator - the other pump turned out to be for heating the domestic hot water, and it turns on only for that purpose.

For the suspect zones, I also double checked that the pumps are actually running. I took off the cap and observed the shaft (?) spinning inside. I didn't observe any that appeared to be seized up or anything.

Even so, for Zone 6, there is never any hot water circulating. I think any heating I feel of the copper pipe is just due to the conduction of the heat from the pump, which gets quite hot. But the tubes farther away from the pump never get warm. (Note: And yes, I did open the isolation valves.)

And for Zone 4, like I've been saying, it will circulate hot water and get the tubes hot if hot water is available...but it never seems to pull up any hot water when running all by itself. Is it possible that the amount of hot water the 4-way valve sends through depends on the flow rate? And maybe there is just not a high enough flow being generated by the Zone 4 pump for whatever reason?

Gordy

Air locked zone. Or possibly broken pump shaft.

Zones getting heat when pump is not on needs flow check. Gravity circulation probably from Dhw calls.

MasterC

So, no comments in a while, and I got busy around here and haven't done any further troubleshooting. Any suggestions for what to try next? How would I diagnose/solve an air locked zone with my setup?

rick in Alaska

This is going yo be slightly difficult due to the lack of proper valve placement, but this is what you can do based on what I can make out in the pictures.
Turnn of boiler and pump power.
Close all valves except zone six valves/ pump. Place mix valve in position 9. Now hook up a water supply to the drain valve at the top of the manifold just before the pumps. Hook up a return/ drain line on the drain valve on the lowest manifold.
Start pressurizing the line to about 25 psi and then open drain line on bottom. Keep flushing water out of the drain until it is bubble free, and try not to get pressure below about 15-20 psi.
If I am seeing all the piping correctly and the mixing valve does like I hope it will, this hopefully will push any air out.
Wish there would have been a couple more isolation valves..
Rick