Monthly Archives: December 2010

DWHR installation

My DWHR unit, or heat exchanger, arrived and I was interested to see if I could manage the installation. The manufacturer provided some good instruction, so I expected the task to work out fine.

I started by tying into the four inch sewer connection near the utility wall. I ran a two inch drain pipe with a slope of at least ¼ inch per foot (or 2%) to the DWHR location.

Because of the heat exchanger weight, I placed a support under the drain pipe near the end and installed a 90 degree long sweep elbow.  I was then ready to connect the DWHR unit.

A Fernco sleeve takes care of the bottom connection, while a ProFlex™ connector is used at the top of the heat exchanger. It provides an almost seamless surface on the pipe interior, which allows the hot drain water to cling to the pipe wall for the best heat recovery yield.

The double wye at the top of the heat exchanger picks up the 1st floor bathroom floor drain, the 1st floor shower drain and the 2nd floor shower and floor drain. The bathroom floor drains are connected to this stack, because it is the simplest and most efficient routing.

I placed the DWHR unit with enough room to the back wall for the ¾ inch cold water connection and pipe insulation.

I will have to take care of the cold water connection, but decided to leave that task for after the basement insulation is complete.

Happy New Year!


That heat is mine, and I plan to keep it!

I have been in framing mode, after having closed up the old basement stairs. I thought it was a good idea to tackle the 1st floor bathroom floor next.


But… there is always a but. This one has to do with plumbing. I have to install the water closet drain, floor drain, and the bathtub/shower drain for the 1st floor bathroom. Along the way, I should think about energy conservation.

All right then, let’s put the framing square aside and get the pipe wrench out.

Plumbing and energy conservation

To reduce our energy load, we included a drain water heat recovery (DWHR) unit in our plans. The DWHR is a heat exchanger with a copper drain pipe that is tightly wrapped with small copper tubing coils.

The unit is installed in a vertical drain stack. The drain water coming down the stack tends to cling to the pipe walls because of the water’s surface tension.

While hot drain water flows down the copper pipe in the DWHR, fresh cold water is flowing up the heat exchanger in the coils and, in the process, picks up the heat from the hot drain water.

In other words, hot drain water enters from the top and leaves cold at the bottom, while fresh cold water enters at the bottom and leaves warm at the top. Makes sense, doesn’t it? Let the drain water go, but keep the heat for which I already paid.

Not recovering that heat can get expensive. The Department of Energy estimates that 80% to 90% of the energy we put into hot water is lost down the drain.

Because the DWHR process relies on the drain water surface tension, it is only effective in vertical applications. The longer the heat exchanger unit, the greater the heat recovery. Also, a larger pipe diameter in the heat exchanger typically yields a better recovery rate.

See also: – Drainwater Heat Recovery

Side note:

A DWHR can lead to pressure loss in the cold water supply, while it is flowing through the small coils around the heat exchanger.

By running multiple coils in parallel around the central drain pipe, some manufacturers have overcome the pressure loss problem. This is something worthwhile to look out for.

Location challenge

What is the best, or the most effective location for the DWHR unit in our plumbing system?

It should be installed at the lowest point possible, which would be somewhere in the basement. That would allow us to pick up and recover heat from the 1st and 2nd floor drains.

Because the heat exchanger would be located on or above the basement floor, we cannot route any of the basement drains through the unit, thus we will not be able to recover any waste heat from basement fixtures.

Waste heat sources

What generates hot or warm drain water that should be routed through the heat exchanger?

The water closet flushes with cold water. No energy recovery there.

The clothes washer is in the basement, thus below the heat exchanger. That doesn’t matter too much, as most of the laundry is done with cold wash cycles these days. Not much energy recovery there either.

What about the sinks in the kitchen and bathroom? There will be some potential for drain water heat recovery. Considering our plans for WaterSense low flow fixtures and the very intermittent use, I suspect a very small recovery yield.

The dishwasher uses hot water. The problem is that it doesn’t draw any cold water when it discharges the hot water. I need both at the same time for the heat exchanger to work.

There are the showers. They will also be fitted with WaterSense low flow fixtures, but they will run for at least five minutes. And I will draw cold water through the heat exchanger while I have the hot water from the shower going down the drain.

After consulting with some energy experts as well as with manufacturers of DWHR systems, I was reassured that I will get the biggest bang for my buck by recovering waste heat from the shower drains.


Quick recap: The DWHR unit will be somewhere in the basement where it can pick up the drain water from the 1st and 2nd floor showers.

The 1st and 2nd floor showers should drain through their own two inch drain stack routing the water into the heat exchanger. The bottom of the heat exchanger will be connected to the sanitary sewer.

Careful placement of the DWHR unit into one of the basement storage rooms leaves the door open for a future gray water collection system. It would fit in the space between the heat exchanger and the sanitary sewer.


Closing up the old basement stairs

We have two very big holes in the basement ceiling that we need to plug. There is the opening were we had the old basement stairs, and the missing floor in the 1st floor bathroom.


I decided to start closing up the floor at the old basement stairs and gathered  a couple of 2 by 12 floor joists, some joist hangers and some left-over plywood sheets .

The new floor will turn the old staircase into a new first floor pantry/storage closet.

Although the existing staircase walls to the left and right were originally cantilevered by a few inches, I felt that it would not hurt to add some support.

To the right, I sistered a two by four to the existing floor joist. It now sits under the bottom plate of the existing wall framing.

To the left, I snug the floor joist partially under the bottom plate of the existing wall framing. This should add sufficient support to the wall as well as the new floor.

Two layers of my left-over plywood became the pantry/closet subfloor.  It sits flush with the existing subflooring to the left and right.

That is one big hole plugged and one small step closer to the basement insulation.


What’s next?

A great weight fell off our shoulders with the passing of another major milestone: heat in the basement. Although it is the basement only and not much is insulated yet.

What we got insulated is the basement floor with rigid foam boards. We also put in the bond break around the basement floor, insulated around the basement windows and installed an additional thermal break onto the window buck.

The next logical step is to get heat into the 1st and 2nd floors and insulate the whole building. Logical as it may be, we also have the big urge to move into the basement – the garden apartment – as soon as we possibly can. Once we live in the building we can continue our work on the 1st and 2nd floors.

In the interest of time, we decided to postpone the heating and insulation work on the 1st and 2nd floors. Instead, we will channel all our efforts into the garden apartment, and continue with insulation preparations. We have the perimeter walls framed out and ready, but more prep work is needed.

I put the usual to-do list together – a list with some major tasks on it:

  1. Frame out the floor at the old basement stairs;
  2. Close up the floor to the 1st floor bathroom;
  3. Install the drain, waste and vent (DWV) plumbing to the 1st floor bathroom; and
  4. Eliminate the thermal breaks along the exterior walls.

Well, what are we waiting for?


The heat is on!

The big day has come. The hydronic heating system is filled with water and Mariusz has come out to start up the system.

He switches everything on and tinkers around with the controls on the boiler. He keeps tinkering but the system just doesn’t want to start up. Should I worry about this?

Sometimes there are simple solutions to apparently complicated problems. As we were getting nowhere, Mariusz took a step back (literally – he stepped out of the utility room) to look at the big picture. I then saw the light bulb coming on. He stepped over to the shut-off valve at the water main and opened it. Of course! A hydronic heating system won’t work without water!

Within seconds the boiler fired up (which is hard to hear because it is so quiet). The pressure gauges kicked in and the pumps began to work, and with a lot of gurgling in the pipes. The temperature gauges at the storage tanks started to climb and the hot water began to flow.

We could see and feel the water running through the PEX loops that feed the radiant floor. I had fun watching Mariusz calibrate the flow rate for each loop at the manifold.

We had, however, two loops that for some reason had no water flowing. That sort of freaked me out. I already saw myself breaking up the new concrete floor trying to find the flaw in the PEX tubing!
Thank God, there was again a simple solution to the problem – a problem that I had caused.

The inlet and outlet for each radiant floor loop are right next to each other, with the exception of the two non-working loops. Here I had placed the two inlets and two outlets side by side.


That meant that the hot water was pushing in from both ends, or trying to get out from both ends. After consulting with Peter, Mariusz quickly identified the problem, switched the PEX connections around and got the hot water flowing.

I can’t tell you how nice it feels to have this nice, warm radiant concrete floor in the basement! The dog likes it too!


Happy Holidays!


Basement plumbing

With the drain, waste and vent (DWV) plumbing in place, we can get started on the basement plumbing. Well, I say we, although the only real thing I was contributing was lots of questions. Peter and Thomas, our installers, took care of the real work.

We extended the water main under the concrete floor toward the back of the basement earlier this year. The stub sticking out the floor has a shut-off valve at the end to which Peter and Thomas connected a one inch copper pipe.


That pipe got extended in the wall toward the ceiling, where it makes a short turn into the laundry room followed by a long turn toward the utility room.


Once we were past the WF steel beam that runs from one end to the other in the basement, Peter and Thomas took the copper pipe up and in between the floor joists with two 45 degree elbows, and extended it into the utility room.


Peter took care of the various fittings and connections to the heating system and hot water storage tanks.


Are we done yet? Not quite. Peter and Thomas still have to install the rough plumbing to the basement bathroom (shower, water closet, lavatory and bathtub) and kitchen. This is where their thinking ahead pays off. All the hot and cold water plumbing fit in place without interfering with the DWV plumbing.

This is a very simplified description of the plumbing work. I will have to dedicate a detailed post sometime in the future on how the system is put together and the various best practices that reduce energy loss and increase efficiency.

With the rough plumbing completed, we can fill the heating system, the radiant floor tubes and hot water storage tanks with water.

I think the never ending stream of tasks just ran dry, and we are ready to start up the system – turn on the heat.


DWV installation

We cut a nice chunk off the never ending stream of tasks with the completion of the PVC to CISP connection , and can now start on the drain, waste and vent (DWV) plumbing.

Actually, most of the drains, or sewers, were installed earlier this year and are now hidden below ground, under our new concrete basement floor.

The above ground drain portion for the basement is limited to the laundry box, utility sink, bathroom lavatory and kitchen sink. Although the Chicago Plumbing Code requires a minimum pipe size of four inches for all concealed (below grade) plumbing, a two inch pipe size suffices for the above grade drain plumbing from the various sinks.

The majority of the DWV plumbing is devoted to the venting portion, which also uses a two inch pipe size.

As with the utility room installation, this task requires spatial thinking skills. Peter and Thomas (the two installers) had to have a mental image of the finished product or final layout before they started the job. Furthermore, they had to account for the hot and cold water plumbing and how it would fit around the DWV pipes.



It appears that we are very close to getting the heat turned on. Yet there is a never ending stream of tasks emerging that we need to complete first.

There is not much plumbing in the house yet, other than the water main coming into the building. To start up the radiant heat, we need the basement plumbing done and connected to the heating system so that we can fill the two hot water storage tanks and the radiant floor tubes with water.

Before we can take care of the cold and hot water plumbing, we need to install the drain, waste and vent (DWV) plumbing. This is basically the plumbing that receives the drain/waste water from the sinks, showers and water closets and connects to the sewer.

But before we can get started on the DWV installation, we have to provide a PVC to CISP connection. The PVC pipes are for the above ground, or non-concealed DWV plumbing. CISP is an acronym for cast iron soil pipe, which are the new underground sewer lines we installed earlier this year.

Do you see what I mean by never ending stream of tasks?

I assumed that the PVC to CISP connection would be a simple gas- and water-tight rubber gasket, the same gasket that is used for the underground CISP sewer connections.

What I did not take into account was the dinosaur in the room, the Chicago Building Code, which calls for an oakum and lead connection from CISP to PVC. Mariusz and his plumbing crew knew about this and got to work.

A special PVC fitting is set into the hub of the CISP. The gap in the hub is tightly stuffed with oakum and at the end topped and sealed with hot, liquid lead.

Why does the code require this cumbersome connection? I have no idea. I can think, however, about a few good reasons why it would be worthwhile to revisit this code requirement.

Why are we allowing – or even worse – requiring the use of hot lead with all its fumes for this connection, considering all the attention and health concerns about lead in our living and built environment?

Why are we requiring a connection that is permanent and non-modular? If, for whatever reason, I have to change something at this connection, I will have to break it (the PVC and probably the CISP pipe) and start over. With a rubber gasket connection, I would have the chance to wiggle the PVC pipe out of the fitting. At the very least the CISP and concrete floor would remain intact.

But that would not only make things easy, it also would make sense. And we can’t have that.


The gas is on!

I put a call into our local gas company to establish an account and have the gas turned on. We scheduled a service appointment and I was waiting for the service engineer to arrive, to remove the locks and open the main valve and meter valve.

As I mentioned in the previous post, we planned to go from three gas meters down to one for the whole house. While breaking this news to the service engineer, I got the look and raised eyebrows. He put his tools back down and said: “Well, let me take a look inside the building first.”

I quickly figured that he was of the opinion that one line (one meter) would not be enough for our heating and hot water load. I gave him the quick tour, showing off our framing preparations for the insulation and took him into the utility room.

What a sight! Not the utility room, but the expression on his face. He quickly admitted that he had not seen a system like ours before. Once the surprise had worn off, he got back on track and asked a number of good questions:

Q: What is the maximum Btu output on the boiler?

A: 150,000 Btu

Q: What is the maximum Btu output on the water heater?

A: There is no water heater. The boiler powers the radiant heating system and domestic hot water storage tank.

Q: What is the peak load of the building?

A: The engineering model indicates that the peak load is 37,500 Btu.

Q: What other gas appliances are in the basement?

A: A gas range. May be a gas dryer.

Q: And the other two units?

A: Each unit will have a gas range. That’s it.

He seemed happy with the answers and explained that our one inch gas line coming into the building has a capacity of around 250,000 Btu. (I think I remember this correctly but don’t take this number for granted!)

With those details settled, we went back outside, where he removed the two redundant meters, removed the valve locks, and opened the valves.

He sent me back inside to open all interior shut-off valves, except the terminal valves (at the end of each gas line). While I was doing that, he monitored the gas meter for movement. If the dial moves, we have a leak somewhere. There was no movement – no leak.

Last check was to open one of the terminal valves to make sure that gas is in the system. We passed that test too.

It looks like we are almost ready to turn the heat on!


Gas service

I am still intrigued about how the one small boiler will provide domestic hot water and space heating to all three units – once it is hooked up to a gas line.


That is our next task. We do have natural gas service coming to the house. It has been shut off, however, since we bought the house back in April 2009. That made the removal of the convoluted existing gas piping in the building easy and safe.


While we were putting a shopping list together for gas piping and fittings, I remembered that I had a bunch of salvaged material tucked away. I showed it to Pete, one of Mariusz’s crew members, to see if it would be of any use to us.

gas-piping-03 gas-piping-04

His eyes were bugging out. It appeared that we had more than enough salvaged pipe and fittings to get us going. I quickly retired the shopping list and enjoyed the thought of the money I just saved by being thrifty.

Before I got my hands dirty again, I had to contemplate the pipe layout.

Right now, the small boiler is our primary source of energy. With the future solar hot water installation it will be relegated to a backup source. That could mean that our natural gas usage may drop so much that the service fees may rival the actual natural gas costs.

In other words, we would pay more in service fees than for gas, considering that we currently have three meters, which each carry the fees. We quickly decided that it makes economic sense to only keep one meter, i.e. one gas line/meter for the three units.


So much for the mental effort. Time now to flex some muscles.

What made the reuse of the salvaged pipe possible was the pipe thread cutter that Mariusz’s crew brought along. It allowed us to cut the salvaged pipe to the desired length, cut the threads into each end, and connect it with the suitable fittings.

We first connected to the one inch stub coming into the building from the gas meter.

From that one inch line, we ran ¾ inch branches to the boiler and to the kitchens in the basement, 1st and 2nd floor for the gas range connections. Along the way, we strategically placed shut-off valves at the beginning of each ¾ inch branch for safety and maintenance. For the last few feet to the appliance, we used ½ inch pipe with a shut-off valve at the very end.

gas-piping-06 gas-piping-07

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This takes care of the gas supply to all three units and it’s time to call the utility company to get the gas turned on!