Hydronic system losing water

[Alternety]

Short question; I have to go out now.
I have a Wiel-Mclain Ultra v2. I believe it is the 105.

If necessary, what would be the best replacement for it?

 

[Dana]

If you have a heating history on the place, run a fuel-use based heat load calculation on the place. This doesn't take hard math or a lot of time.

The 94 MBH DOE output of the Ultra 105 is more than 2x oversized for 19 out of 20 houses out there, and if you can down-size to something more appropriate, you should.

The aluminum heat exchangers on the Ultra are more sensitive to system chemistry than most stainless steel boilers. Stainless fire-tube heat exchanger boilers with big turn-down ratios and lower pumping head are proving to be a better solution in most cases, but you probably don't want to blindly drop a 100K stainless boiler in where the (most likely oversized) Ultra 105 has been if a 50-80K unit would have you covered, and deliver a wider modulation range. The Ultras have a 5:1 turn down ratio, many fire tube boilers have a 7:1 or 10:1 turn down, but the lower the min-fire output the less cycling there will be on zone calls. If it's determined that your design heat load is 25K a 100K boiler with a min-fire output of 9.5K is still doing quite a bit of shoulder season cycling, even if it's less cycling than the Ultra.

 

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[Alternety]

Thanks. I am well acquainted with the issues of the WM boiler. If it is the problem, this will be my second replacement core. I do not want aluminum again. The 105 is about right for the load. 6000 sq ft, greenhouse, pool, 3 car garage, and DHW. Very good insulation. Southern exposure with a lot of insulating glass.

A short history of the system.

Teckmar controls. Controls were obsolete when installed. And the installed wiring will not allow the new communication streams from current Teckmar equipment.

Most (or all) manifolds and valves were very obsolete when installed. No replacement parts. I have been considering a complete re-work of manifolds and valves. One room is always on, because the valve no longer functions. Unfortunately the room is not a sauna, but an office.

To deal with garage and greenhouse, the system was initially filled with antifreeze. It ate the original core of the boiler. Turned out the antifreeze was known to be faulty and very acidic. Company that made the antifreeze would not honor the recall they had made or any repairs. They "had been bought", so they had no responsibility.

In addition to everything else, the contractor used crimp connections for all the copper piping, and they all leaked and look like crap. Crimp product vendor: If it does not hit the floor it is not a leak. When the house gets sold in the future, many thousands of value will be lost as soon as they go into the utility room.

Thoroughly (I thought) flushed the system. Although recently I was exposed to some of the fluid and it does not smell clean.

I put in new core. All of this took place over Christmas and New Years. You can imagine how that worked out.

So now I need to look around to see if I can see a leak anywhere. A few weeks ago I noticed that the water level was a bit low, so I brought it up to the normal level. Over the last days/weeks I have heard odd noises in the house. I finally realized it was gurgling in the hydronics. Went to the boiler; pretty much zero water pressure.

Now I am going to try to find where the water is going. My first thought is some work going on that could have damaged some Pex. I am going to go all over the house to see if there any visible leaks (e.g., wet spots in a ceiling). No leaks in the manifolds. I have turned off the system. I am going to try to see if there is any water coming from the condenser drain on the boiler. That would point to a leak (e.g., ate a hole in the core again).

So, if I can be pointed to a proper replacement, I may need one soon.

 

[Dana]

With Weil-McLain's lineup (assuming you're still willing to deal with them) the ECO-110 stainless fire-tube boiler has comparable 5:1 urn-down ratio and other features.

On the lower cost/higher value end HTPs UFT-100W stainless fire tube boiler has a 10:1 turn down and a dedicated pre-plumbed port for the indirect water heater. It can almost always be pumped direct (no primary;secondary required).

The Westinghouse WBRNG110WPU (= HTP EFT-110) has very similar capacity & turn-down ratio as the ECO-110, and (like the UFT-100) separate port pre-plumbed for the indirect water heater.

The Lochinvar WH-111 and KH-110 (floor mount version) fire tube boilers have similar capacity, and a 10:1 turn down.

The Triangle Tube PA110 or ACVMAX 110 would also fill the bill.

Hopefully you'll find an easily repairable leak elsewhere in the system and you can cruise awhile longer on the Ultra 105, having just repaired it.

 

[Alternety]

Dana,
It does appear that the boiler heat exchanger is at fault.

When I first saw the problem, I turned the system off. Pressure gauge was close to zero. There was still dripping from the condensate pipe even though the boiler had not run for several hours. I left the system off and let it sit for a day. I came back; no drip. Zero pressure. Turned the water refill on, left the boiler off. Drip. So I am concluding that there is a hole in the boiler containment. No other source for a drip.

I have started looking for a boiler. I will not have another Al heat exchanger. The ECO-110 is interesting. It is a stainless steel heat exchanger. It is smarter and would also let me transfer a number of the functions currently handled by the pretty old Tekmar controllers. That has some merit. On the downside, except for the air/exhaust pipes, nothing on this model matches any of the piping on my current boiler. It will be a major re-piping project. All the water pipes come out the right side; this is where the wall is. The Ultra-105 has the pipes coming out the top. I will need to move pumps and a bunch of pipe. And there is little space. If I move the boiler to the left it might work better for the pipes, but the air supplies will be harder. I am looking at how that will all work out. It is going to be expensive.

I am not adverse to WM. Except for the stupid Al heat exchanger, I have been happy with it. It does what it is supposed to do and is reliable.

If I do a replacement, I am going to change the circulator for the system. My initial design used a Grundfoss variable speed pump with an external pressure differential controller. Unfortunately, when I explained what I wanted to the contractor, I was not sufficiently clear. I wound up buying a box for several hundred dollars that had no relationship to what I wanted to do. My change will be a Taco VR1816 smart pump. I have been trying to figure out the differences between some of the related data on the Taco site. I have always found the Taco site to be confusing and lacking necessary detail. But that pump is sort of the ultimate pump. I have been following it for years.

I am currently trying to recall and find data from 15 years ago relating to pumps and things. My big question at this point is to determine if the Taco pump is appropriate for the system. I did not get loop lengths when they were installed. I need to be sure that the Taco pump (18 ft head) is sufficient. I think it is. It is a closed loop system many controlled valves. The actual flow rate is less important, because it is is on the low side, the system will simply supply heat longer. Everything other than the DHW (which is on a separate heating loop) has very high thermal inertia.

A question I have is about turn down ratios. I am not sure how to evaluate that as a purchasing decision. How does it impact this closed system. If it does not alter overall efficiency, I probably should not care. Could you please explain the trade-offs? Although the 105 has this function, I have never "seen" the utility of it.

The WM ECO-110 was your first choice. May I interpret that to mean it would be a good idea to concentrate on that boiler?

 

[Dana]

During the shoulder seasons the instantaneous heat load will at some point drop below the minimum fire output of the boiler, and even with a perfectly tuned reset curve it will be forced into cycling on/off, which is less efficient than modulating with ultra-long burns. The lower the min-fire output is, the less cycling there is, assuming a reasonably well tuned system. If the house is cut up into a gazillion zones, some of the zones may not be capable of emitting the min-fire output of the boiler, but the lower that number is, the fewer cycles there will be when serving low-radiation zones. If it's all high mass radiation it might not matter much, since the thermal mass extends the burn times.

I'm not partial to the ECO-110 over the others, other than the fact that you're already familiar with the local tech support for their products (be it good bad or otherwise), whereas the others are unknowns.

 

[Alternety]

I only have 0.7 gazillion, but I get the idea. Everything is embedded in concrete. And there is a large buffer tank between the boiler and the heat sinking parts.

I have looked at the ECO-110. I really like it. Stainless core. 10-1 range of fire rate. The one drawback is that all the pipes come out in a different place. It would require a significant re-piping. That would probably cost a significant percentage of the boiler cost. The boiler is fairly smart. It can do a significant amount of what the Tekmar controllers currently being used do. I am going to need to think about what to do. May want to transfer some functions to the boiler.

They are still doing the Ultra line. This one has essentially the same piping as my current Ultra. So, trivial piping. The Ultra 4 has the same brain as the ECO; but still 5-1. I have had some conversations with WM tech support. The guy I talked to was quite helpful. They have apparently gone through some iterations on the Aluminum heat exchanger. They are now putting a protective coating on the Aluminum core. If that actually works, the Ultra 4 would be my best choice. Same smart controller, no re-piping. I am torn about the core. I am guessing that I could put the revised core in my existing boiler. I did not think to ask when I was talking to tech support. My existing boiler is out of warranty, so buying a core is an appreciable fraction of a new boiler.

I am also going to review my boiler room piping. Looking at the documentation for the boilers, I am not sure what I have is correct. Whatever I do I am going to replace the circulator for the load to a Taco VR1861-HY2-FC2A00. This became available when it was too late for my installation. I tried a Grundfoss variable speed circulator, but it was a primitive speed control device at the time and way too noisy. If anyone has had any experience with that Taco circulator, I would appreciate any feedback. I had a number of conversations with Taco tech people when I did my system. I really wanted one, but it was just not ready.

At least it is getting warm outside. Last time I needed a core was through Christmas and New Year. As I sit in my office, it is 68 degrees. The boiler has been off for most of a week; and the sun has not hit the windows yet. Last time, I spent a small fortune using quickly purchased electric heaters to keep plants alive.

 

[Dana]

The turn down ratio of the ECO-110 is (110,000/22,000=) 5:1 , just like the Ultra, not 10:1.

If you have sufficient buffering already built in to manage the Ultra, it'll work just fine with the ECO-110, which has only slightly higher output.

If it saves enough on the installation cost to go with the new-improved Ultra, that may be exactly the right thing to do in your situation. Given your experience you might want to find out about possible extended warranty options too.

 

[Alternety]

I believe the documentation said 10-1. It does not really make much difference to me; I think.

I fear the Ultra core. It would be seriously easier; but I have developed a real allergy for WM Aluminum. The ECO-110 would also give me incentive to replace the hideous piping I have that leaked and corroded. The system is designed to handle zones exposed to freezing conditions. I don't feel I can risk those crimp connections to survive with a different mixture. I do not really want to have 10 55-gallon drums that need to be removed rather than the 5 I have in the yard now.

I am going to be wandering around the boiler room measuring and reviewing current piping configuration and components. Trying to get a feel for what has to be done. When I found the system pressure at zero, the low water device did not do anything. I am not sure how it decides there is a low water event, but zero pressure would seem like that condition. However, there was still water in the system. So maybe that is not considered low water.

 

[Dana]

I linked to the marketing documentation that clearly states 110MBH max, 22MBH min. Section 1.F. of the specifications document also calls out "Boiler shall be capable of full modulation firing with a turn down of up to 5 to 1. ". That seems pretty clear that it's a 5:1 turn down boiler not 19:1, not that it's going to make much of a difference in your system.

 

[Alternety]

I thought I saw a 10-1 statement in the documentation. I appears I was hallucinating.