Replacement Dunkirk In-Floor Wide Temp Swings and Overshoots

John_199

Could one of you great folks take a look at the photos and let me know where the mixing valve needs to go in the piping system. Thanks, John

John_199

Replaced Old Boiler With Dunkirk Wide Temp Swings Overshoots

A local contractor has replaced my old Kohler boiler with the correct size Dunkirk PWX4-ENG2 for my in-floor (slab)one zone system. The system only runs once a day for a very long time and then over shoots the thermostat by 4-5 degrees.

The return water to the boiler is less than 120 degrees which is of concern. How can they modify the current piping to get the system to cycle and avoid the wide temperature swings.

I appreciate any help you folks can offer. I have attached photos of both the the old and new system. Thanks, John

Al Corelli_2

Bypass?

What position is the bypass valve in?

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John_199

There is no bypass valve. I'm sure there needs to be one but the contractor is trying to make it work without one. He has done lots of radiator type boiler installs but told me today that this one has him puzzled. Can you tell by looking at the photos where it should be installed? I think on the old system the bypass was the large red thing above the boiler. Thanks, John

Paul_11

FIND A COMPETENT HEATING CONTRACTOR

With radiant heat, you need some way of mixing the boiler water temperature down to a hight of 120 and way below most of the time.

But you need to keep the boiler at 140 or above.
Do not try to do this without some type of mixing system.

Get some help.

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Al Corelli_2

Isn't that pipe...

Isn't that pipe that seems to run behind the water heater a bypass? I don't mean the smaller diameter gas line.

Appears to be a "boiler" bypass with a plug cock just above the water heater.

Can't really see what was done, but I think the circulator should be mounted on the supply from the boiler. If I am seeing what I think I'm seeing, moving the circulator would make that pipe with the plug cock a "system" bypass, and in my opinion, should improve the flow of heat.

There are other details that I do not see, but maybe more pics will show them. I see no way of tempering the water for the radiant panels. Was there a device called a "Panel-Trol" installed on the old system?

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John_199

More Pictures

I've added 3 more picture with more detail. My contractor has said he will get the system operating properly. Here in Indiana hot water heat is a rarity and in-floor almost unheard of so to find someone who will even install a boiler is rare. Most people wanted me to put a gas furnace in the attic.

The valve by the water heater would be tough to adjust. My assumption is a new bypass valve would be a lot easier to adjust and tweak. Thanks, John

John_199

Thanks Paul

My contractor is very concerned about getting the system right. Any help on valve placement and piping configuration would be appreciated. Thanks, John

Bruce M

Age and Type of System

Am I correct in thinking that this radiant system is from the 1950's? Is it copper pipe or black pipe in the floor? Do you know the water capacity of the old Kohler? The water capacity of the new Dunkirk? What temperature settings were used on the Kohler? Do you have a copy of the original plans? Sometimes they are filed with the building plans if any were required in your locale. It looks as if the original system was well thought out.

John_199

It is radiant from the about 1954. Copper pipe in the floor. It was a Kohler "22" boiler. No building plans available. No temp settings were on the old system. It had been messed with over the years. There are 8 copper loops coming out of the floor to a common manifold. I think the big red valve above the old system was the mixing valve. Also there was an outside sensor in the old system but I'm not sure what it controlled.

There is no mixing valve installed with the new Dunkirk which I think is the root of the problem. My understanding is that the supply to the floor should be at 90 to 120 degrees max and that the boiler needs return water at 140 to 150 degrees to not be compromised.

Thanks, John

Weezbo

looks to have a solution for a boiler by pass or system by pass.

one way would be to put a by pass on the boiler the other looks an easy by pass on the system,

the boiler solution would be to lose the 1"plug at the temp pressure gage ad a nip and "T" reinstall the gage nip out to a I series S from Taco then down to the plug add a nip and T install another temp gage so you can visually see the temp...

the other is lose the large nip in the re cir line add a "T short nip to flange come off that "T with a riser to an I series S over to the same T at the temp pressure gage,

on the Cheap a ball valve would provide some hit or miss by pass type boiler protection. if you put ball valves on both take offs you could add a circ and do pumped by pass with a Taco temp respondent Circ set for 138 140 ...depends on flow.




thats the boiler side of partial differential set back the field side in an indeterminable concrete slab could be another side issue ...

your out side air temp controls lashed into the mixing valve you had.

Bruce M

1950's System

It sounds like you have a really nice 1950's system. I would look to run water at a temperatue of 85 F for an uncovered floor. I would look for a return differential temperature of 18 F (85 F - 18 F = 67 F) for an uncovered floor. Uncovered meaning no rugs, etc. Does your distribution manifold have a name or model on it? Are there any markings as to what the various entry and exit points are on it? Is there any thing near your boiler marked Panetrol? Is your domestic hot water provided by this boiler?

John_199

I have about 2/3 carpet and the rest tile on about 1400 square feet. The distribution manifold does have name on the side I can't get to. The techs are on their way and I'll see if they have an inspection mirror.

From the way the other piping is set up I think they are either all entry or exit ports.

There were 2 boxes taken out at the install and one could have been Panetrol. It was about 4" by 4" and located above the shut off fuse/switch. What it it was a Panetrol and was removed. does that impact my solution?

Domestic hot water is separate.

Thanks, John

heatboy_2

For the price of......

..... an 1.25" mixing valve that does nothing to protect the boiler, you could purchase a variable speed reset control that will modulate floor water temperature while protecting the boiler from condensation issues. You have to re-pipe the boiler, but from the looks of it, you would have to do that anyway to add a mixing valve.

Bruce M

Panetrol

I would ask the installer and find out what he did with the 2 "boxes" that were removed. Very often they may be lying in the back of a truck or in a scrap pile. It is obvious that your system was originally installed by craftsmen that knew their trade well and were experts. In the case of a 1950's sytem such as yours, it is often better to use the original parts. I am sure I will get a lot of people that will not agree with that. You were wise not to install a furnace when you already have such an elegant system. There are of course, modern mixing systems. I believe if you go into the library here that you will find information aboout Panetrol which I believe was made by Taco. Go to the library and read about these radiant controls from Honeywell:

http://www.heatinghelp.com/pdfs/138.pdf

Bruce M

The Library has a very informative copy of the information for your old Kohler 22. Look here.

http://www.heatinghelp.com/pdfs/411.pdf

John_199

Thanks Bruce. The controls that are long gone were the ones listed. I did not find the big red valve in that literature but the controls and boxes matched up. Wow what a great Kohler 22 brochure. I kept the ID plate from the old unit as a keepsake. My grandparents built this house and I still have all the Kohler bath fixtures and kitchen sink. Looks like we are going to new controls. Thanks, John

Bruce M

Paneltrol Link

Here is the link to the Taco Paneltrol. It is also in the Library here;

http://www.heatinghelp.com/pdfs/56.pdf

Bruce M

Kohler

Your grandparents knew what they were doing. Nothing better than Kohler. It is nice that you appreciate good quality.

John_199

Contractor was back today and tried adjusting the valve shown next to the water heater with no effect. He is going to repipe the boiler. Rehau makes a variable speed mixing module # 281731-001 that looks like what you are talking about. It also includes an outdoor reset control. Is that the unit you are talking about? Are there others out there that are better. Thanks, John

GLENN_14

have your contractor print this literature

There is a great piece of literature on the Weil Mclain web sitewww.weil-Mclain.com/downloads/literature/apex/apexcpw.pdf it covers near boiler piping technical information for a whole series of piping options. your contractor will find this very useful

Bruce M

Dunkirk Installation Manual

John, you need to go to the Dunkirk web site and download the installation manual for your boiler. Look on page 6 where it says:
"If the boiler is to be used in a heating system where water temperatures below 140ºF are desired (e.g. radiant floor heating, a 3-way or 4-way mixing valve or suitable alternative is required to prevent low temperature return water from entering the boiler. Follow the mixing valve manufacturer’s installation instructions. The minimum design return water temperature to the boiler to prevent
condensation in the boiler and venting is 120ºF. The minimum high limit setting is 140ºF." Here is the Dunkirk site:
http://www.ecrinternational.com/secure/upload/document/388.pdf

Ross_7

Pressure relief valve

It looks to me like he installed a bushing on the pressure relief valve, and downszed the outlet piping, which is not to code. You'd better have him change that also.
Ross

John_199

I'm inclined to go with the suggestion from heatboy below so we can can get precise, adjustable temps to the floor and have the advantage of outdoor reset without having to tweak the mixing valves. He has been in contact with Dunkirk and is very aware of the low temps being a problem. Would you know how to configure this on my system? We have a copy of the Weil-McClain maual that covers a variety of near boiler piping options. Too bad there is no one in my area (Indianapolis)that could help get this concluded fast. Thanks, John


"..... an 1.25" mixing valve that does nothing to protect the boiler, you could purchase a variable speed reset control that will modulate floor water temperature while protecting the boiler from condensation issues. You have to re-pipe the boiler, but from the looks of it, you would have to do that anyway to add a mixing valve."

John_199

Thanks a lot Ross. It's on the list. John

jim s_2

Also

not too wise to thread both ends of the relief pipe.

leave the outlet end bare so no one will be tempted to cap it in the future if it shows signs of dripping.

Tony_23

Where

Where did he put the aquastat ? It's not on the well where it normally is and I don't see it. How is he controlling the water temp of the boiler w/o a high limit ?

What type of thermostat do you have ? The cycle rate might just need some adjusting. Are you setting back the temp at night ? That will cause a long run time w/overshoot on a high mass system like you have.

My interim solution would be to open that 3/4" bypass valve fully and throttle back the supply valve to the floor loops so you get more bypass flow. Water follows the path of least resistance. This only until it gets repiped.

John_199

The aquastat is mounted on the supply fitting just below and left of the temp/pressure guage with the 2 wires coming out. 2nd group of photos (dsc_0001). I assume thats the aquastat. Am I correct?

New Honeywell thermostat TH6000 series. I'm sure it is set up correctly for the system. No night set back. The system overshots and under shoots so badly it basically only cycle once a day.

Should I cut back the blue handled valve coming out of the boiler supply line to cut the flow?

Thanks, John

Tony_23

Aquastat

I can't see one, it's not in the normal location and I don't see it.

Do not close that ball valve, it won't help.

Where is the circulator ? It must be after the bypass tee, right ?

heatboy_3

tekmar......

..... has a few models that would work for you. From a basic 356, which supplies mixed reset and boiler minimums to the more sophisticated 363 that does what the 356 does plus boiler reset and, in your case, future domestic hot water production.