Hydronic Boiler on Monoflow Radiant system

CVG_Kid

I will try to make this short with only the essentials. First the urgency is the weather this week in Ohio. It will be bitter.

I have a four family apartment building currently only occupied by myself. It has a Climatrol boiler feeding a mono flow system with cast iron radiators. The system has not been used in the past 5 years or so. I had frozen/cracked radiators and with only myself in the building just spot heated. Over the summer I fixed the radiators by removing sections and in one case a very small crack with JB Weld. I also added hydronic thermostats to the radiators so I could run the system and turn down any unoccupied spaces.

So today when I went to fire the system it was the first time in five years or so.

I opened the water supply actually thinking the system would fill with the boiler off so I could bleed it and check for any leaks since I've literally had every radiator disconnected at some point. There was no water flowing. I guessed that perhaps the boiler pump was required so I decided to fire the boiler.

My process was:
1. open gas valve to the boiler
2. light the pilot
3. depress some button
4. open the electric valve

It's been a long time but it lit fine and I had fire. What I didn't have was the feel in the pipes of any water filling the boiler. So I switched on the pump but still didn't feel any water flowing to the boiler.

I attempted to confirm this two ways. I opened the boiler drain and got a hiss of air but no water draining. I also opened the emergency pressure valve and there was barely a trickle of water.

I've shut down the boiler pending your help concerned with the effects of no water flow.

This leads me to conclude I have a water supply problem to the boiler. I just need confirmation of this and maybe some advice how to proceed.

Please forgive any wrong names for parts/functions. I'll include some photos below.

I really really appreciate your help and insights.

RobG

First, it sounds like you just dry-fired your boiler, which is the easiest way to kill it. It sounds like the fill valve is not working. If the place froze up as you say, the first thing to do would be to air test the system at about twenty pounds to see if you have leaks. If you find that you have no leaks replace the fill valve and backflow preventer and bleed the system. Hopefully the boiler did not get damaged by the dry-fire.

CVG_Kid

Thanks for looking at my issue and your response.

The system was previously drained so when I fired there was nothing in the boiler. It was fired maybe 3-4 minutes before I shut it down. I hope that would not 'kill' it.

I do not know how to air test the system. I would have to do some research if that's the consensus.

I did do some further investigation. Can someone help me identify the parts in my first photo? Is the valve on the left the pressure regulator and the valve on the right the backflow preventer? Between those two and the flow valve is a union. I did disconnect the union and there is good water pressure.

I can only conclude the water flow issue is between the supply valve and the boiler though there is very little between except the two valves in that first photo. Is replacement warranted? Are they known to be an issue if they set for a long time?

Thanks again.

icesailor

First of all, I have never seen a "small crack" be repaired with J-B Weld. My old High School (19620 Auto shop teacher used to say "You can't buy a mechanic in a can". j-b- Weld fits that definition.

If it is a four family house, you are not a professional doing the mechanical work, you are a DIY homeowner, renting rooms.

That "valve" you show is probably illegal to be replaced. Its not legal to install them on new applications.

You should have called a Professional years ago.

You sound like you are at the beginning of a water damage disaster.

kcopp

you really need to bring in a professional who can figure out what works and what is toast. Open and drain as much as you can.

CVG_Kid

The entire system has been drained some time ago. My issue is filling it again.

The JB Weld will hold or not. It was a barely visible hairline crack. Others reported success using the same. If it were not the end piece of the radiator I would have removed it.

I appreciate the advice to bring in a professional but unfortunately I'm out of work right now and money is very tight. I'd appreciate instruction, guidance and advice in bringing the system successfully online.

I will be replacing the boiler and likely some lines in the spring but this is where I am now.

RobG

We really don't have enough info to help you. Can you post more pictures of boiler, boiler room and piping.

CVG_Kid

Thank you. Yes. Here are a couple.

The water flow is uninterrupted from the house meter. It then meets:

Supply valve >
Union >
(2 valves in the picture) Backflow(?) >
Pressure Regulator(?) >
supply valve >

Here it splits one half going to a supply valve and the expansion tank. The other side goes to a union and after that terminates in a 2" (or so) return pipe which goes to the boiler.

As noted above, I am not a professional but DIYer trying to fix an existing installation and learning as I go.

RobG

I cant quite tell but is there a ball valve that is closed in between the fill valve a the boiler? In one photo there is an open ball valve and in another one is closed. The ball valve with the green handle is closed.

CVG_Kid

Thank you. Yes. It WAS open when I was attempting to fill the system. I shut them though after there was no water flow.

Am I correct that the bronze valve with the relief handle and drain pipe below it is the fill valve? If so, there is only a trickle of water when I lift the relief valve. Is this a good indication that either the fill valve or the valve next to it (backflow preventer) are at fault?

Jamie Hall

And a very expensive journey it may be.

First -- as has been said, at this point you absolutely have to pressure test the whole system --- boiler and all -- with air. Don't do it with water. You might get lucky. You might also need a boat. An air test is simple -- rig up something to connect an air compressor to a convenient fitting. The boiler drain will do nicely. Run the pressure up to 20 psi. Watch it for a couple of hours; it it holds, you don't have a leak (yet). If it doesn't, you do and you need to find and fix -- properly -- the leak (I've used JB Weld for steam, at less than 1 psi. I wouldn't use it for water, at 20 times that value!).

Assuming no leaks. As has been said, replace the backflow preventor and the pressure reducing valve. You need new, up to code (you are an apartment building; you must meet code) units.

Now with the boiler drain open, try running water into the boiler. It should come out the drain... and nowhere else. Close the drain. There should be a pressure gauge on the boiler somewhere. Fill until you have 20 psi or so. And again let it sit for a while. If it holds, you are up to step 2 successfully.

Now, before you fire that poor boiler again, you will need to bleed all the air out of the system -- and for use to help you, we need a lot more information about your system.

RobG

Do you feel lucky? If you do, and you own the property, close both ball valves at the backflow / fill valve. Hook a garden hose up to the boiler drain and fill the system with water (not to exceed 20 PSI. You will need two people and cell phones, one to open the hose bib and monitor pressure and another to bleed the radiators. I would recommend air testing. The question is, Do you feel lucky?

CVG_Kid

Well I asked for, appreciate and weigh ALL the comments and help.

As a result of your input I am trying to figure out the air testing. I don't have an air compressor but can pick up a pancake compressor. I was just trying to work out the connection to the drain in my mind and what gauge I'll need.

It does still seem however that the fill valve is faulty based on my original test and I should be sourcing a new one. Yes? And if that's the case then I suppose I wanted to ask why a previous poster said the current one was likely illegal so I can buy the right fill valve.

Ironman

Caution! That is NOT a fill/backflow assembly. It IS a fill/relief valve assembly. If you replace it with a fill/backflow, the system will have no relief valve and become a potential bomb that could level the entire block.
You will have to install a relief in addition to a fill/backflow.
Even though you may not have the funds to hire a pro, the laws of physics are immutable and respect no person. Do the wrong thing and the consequences may be devastating and deadly.

CVG_Kid

So IceSailor characterized it as illegal because there is no backflow prevention? I assume that's the current code then and something I would need to add?

Something like this?
http://www.supplyhouse.com/Watts-0386463-B911-1-2-Bronze-Combination-Fill-Valve-Backflow-Preventer-Threaded
(mods if links are not permitted, please remove with my apologies)

CVG_Kid

So I would install both linked in order of ...

supply
backflow prevention
fill valve
relief valve
boiler

And this will save my neighborhood from a crater where my home used to be?

icesailor

@ironman:

Ironman speak truth.

The reason I mentioned that the valve you have may be illegal to replace is because it is very expensive, and sucks as a relief valve in the location it is usually installed in. So, some DIY's skip the second part with the relief valve part. THEN the boiler is a bomb.

If you are brave and decide to try what some have suggested with a hose, get a good, non-leaking garden hose with good male and female connections. You need a double female washing machine hose. Connect to a street source and the other on the boiler side. When ready, turn on the water and fill with pressure for one minutes, tops. Shut off the valve. Listen for air hissing. If you hear any around the boiler, if they are air vents, close them. If it holds pressure, fill for two minutes. Shut off the hose. Go upstairs. Open a radiator air vent, If you have air pressure, you MIGHT not have any leaks. If you don't, you probably have leaks somewhere. With help, someone adding water, you might find it.

Far better to use an air compressor. Its a lot easier to clean up a air leak than a water leak.

Myself personally, I never look for leaks with water. Only air.

Buena Suerte

CVG_Kid

"The last device heats the water." Funny.

I'd like to ask another question about converting this system. My first step was to fix all the radiators and zone them with thermostatic valves. This part is done.

My next step is tied in with my remodel. I'd like to put radiant heating in the floors of the new bathrooms and possibly other living areas replacing the existing cast iron radiators. Eventually there would be a new boiler and separate zones for the old radiators and in floor radiant tubing.

This led me to a few questions:

1. What is the best/proper way to disconnect a radiator from a monoflo system? Can I cap them in the basement or must I create a bypass or must I remove the monoflo T from the main distribution line?

In the bathrooms I will be tiling during heating season and want to replace them with infloor radiant.

2. Radiant floor would be distributed through a manifold and not a monoflo system. Is this correct? I understand the flow resistance of radiant tubing and cast iron vary so I'll need separate zones.

3. Can I convert first floor living areas to radiant heat under the sub floor with first floor apartments having hardwood some planks exceeding 4 inches in width? I've measured the thickness of hardwood and subfloor at 1.75 inches. (see pics)

Finally is that all doable in the end? Sub-floor radiant heat on the first floor. A mix on the second floor of cast iron and sub-floor (bathroom only). At least two zones. The old cast iron on the monoflo system and the new sub-floor radiant on a manifold with a high efficiency condensing boiler.

As previously observed, I'm not a professional, as is self-evident, just a motivated DIYer. I will bring a professional in toward the end pre-inspection to review my work. I want to pay for brain work and bear the grunt work myself.

I appreciate all comments and input.

SWEI

1.75 inches is a bit on the thick side. You'll need to run the numbers to see if a reasonable water temp will deliver the BTUs you need into the space above. Use extruded plates and insulate well below them. It will take a bit of care to avoid those X braces between the joists.

CVG_Kid

What calculation is that?

I AM trying to do this right. I was previously leaning on existing BTU in the radiators but found the 1944 installation appears oversized so I'm working on a heat loss calculation now.

Ironman

An accurate, detailed heat loss like an ACCA manual J. SlantFin has a free program that you can download.

An accurate load calculation is the foundation for any heating design.

As SWEI said, with the thickness of your floor, it may not be able to produce enough btu's for design temp. The heat loss calc is necessary to see what your load is.

Trying to do radiant in a bath room when the rest of the system has CI rads is usually gonna be very problematic. An electric radiant grid is usually the better way to go.

CVG_Kid

Thank you.

I'll check out the SlantFin program. I also saw online agencies that will do the calculation for a small fee.

I"ll also look at the electric radiant grid.

Any recommendations for properly capping those bathroom CI rads on a monoflo system?

Ironman

You cannot simply cap off the lines as that will more head to the system and reduce its flow.

You either have to pipe the bull of both Tees back together or remove the unused Tees altogether.

You mentioned that you installed TRVs on each rad. If you didn't have a bypass with each one, you've created the same scenario.

A mono flow system must maintain full flow through each radiator connection that comes off of the bull of the Tees.

icesailor

TRV's are a good idea that can have bad unintended consequences.

Just like IFC's.

CVG_Kid

That was my understanding as well. Thanks for the confirmation. I will likely do a bypass (pipe the bull of both Ts) in the basement.

On the TRV's, I read and read and there was mixed debate on their use in a monoflo system. In normal use my TRVs should have only slightly reduced flow for balance and comfort when in use. I kept the old valves as well.

I read extensively on the electric radiant grid you mentioned. My initial concern was energy use. I found it difficult to project the BTUH produced by the grid and several comments suggested it was useful to warm the floor but not to heat the room.

Wouldn't zoned hydronic be better in that application?

Sorry so many questions but one more...

I also was reading warmboard's site. Knowing I have thick hardwood floors I was curious about doing hydronic in a wall or ceiling application? I have plaster over cementboard on walls and ceilings. Any experience with this?

icesailor

"Boiler By-Pass's"

I don't know what you refer to as a "boiler by-pass" is, but what my old dead Wethead boss always did (and I was taught to do) was to connect the supply and return at the boiler together with a balancing cock to try to make more hot supply water return to the boiler. We ALWAYS put them on BAB's. We also used Everhot external tankless's that were 2" as bypasses and the reverse acting "B" control shut off the circulators if the boiler return got too cold.

wmtandson

I have been doing this type of work for many years and when I read your posts ,I fear for you.
A simple fill valve had you baffled and now you want to take on Radiant floors?

CVG_Kid

Thanks for your responses.

I'm certain I'm using the wrong term but what I intended to do was remove the bathroom CI radiator from the monoflo loop and then connect the supply and return from that branch in the basement so flow is not inhibited. I'm rethinking retaining the monofo system though now.

While I appreciate the ridicule I do wish it were more instructive. Two posters have eluded to the complexities of radiant floors. I'd benefit from an explanation of what makes it complex and your experiences.

If it helps, I grabbed a copy of Modern Hydronic Heating for a more disciplined approach.

icesailor

@CVG-Kid:

I hope that anything that I saw is seen as ridicule. I don't ridicule anyone. I try to use dry humor and understatement as a way to make a point.

I wasn't born knowing anything except what my mother encouraged me to do when I was first born. Which was drink.

After that, I have been on my own.

From what I read in your last post, you have been seeing the light.

KISS: Keep It Simple but don't be Stupid.

CVG_Kid

No. I do lack competence when it comes to this. My experience is if you don't know something just be up front about it you won't waste as much time pretending you do. This is not my field, it's not going to be, but I'm working on a better understanding for my own applications.

I do think I've complicated the issue by not designing a new system from the start. Instead I worked backward first fixing the frozen radiators, then trying convert part of the system with kitchen and bath remodels I'm doing and then later intending to figure out the mechanical room changes.

I'll air test the system as suggested and fix my fill valve this week, I'll take out 2 bathroom CI rads so I can remodel and get a better idea of my end game before going further.

Ironman

CVG_Kid said:

Thanks for your responses.

I'm certain I'm using the wrong term but what I intended to do was remove the bathroom CI radiator from the monoflo loop and then connect the supply and return from that branch in the basement so flow is not inhibited. I'm rethinking retaining the monofo system though now.

While I appreciate the ridicule I do wish it were more instructive. Two posters have eluded to the complexities of radiant floors. I'd benefit from an explanation of what makes it complex and your experiences.

If it helps, I grabbed a copy of Modern Hydronic Heating for a more disciplined approach.

After reading that book, you'll see there's no simple explanation that could be posted here. That's a college level course book. I would recommend that you get one of more basic books that Dan has available here on site as a starter.

CVG_Kid

Thanks. I'll have a look. I flipped through it last night. I didn't have any concerns with the college level material. It does not seem to address older technologies though in existing installations so I'll take your suggestion.

icesailor

New technologies are just old ones revised. Not always an improvement. Just cheaper.

RobG

This would be the unit you need. For code purposes you will also need a backflow preventer.

http://www.taco-hvac.com/uploads/FileLibrary/100-3.5_Boiler_Feed.pdf