How Fast is Boiler Damaged With low IN and Out Temps?

RonWHC

which there can be no disagreement. Every code, in every jurisdiction, everywhere, forbids reducing the outlet of any pressure relief valve. Your guy did it. Yell at him now.

That heavy black steel pipe hanging, unsupported, off the valve is also a no-no. Safety first.

John_201

How Fast is Boiler Damaged with Low In and Out Temps?

I have a Dunkirk Plymouth Extreme boiler that was installed incorrectly and has been running now for 2 months with low input and output temperatures. It can't get above 120 out and I assume return is about 100. It now pops and cracks on start up and did not do this when first installed.

Can this boiler be damaged or have it's life shortened by running under these conditions for almost 2 months?
Thanks for the help

Derheatmeister

Have seen busted boilers!

I Do not know this boiler, but if it is a cast iron boiler then you should protect it from the abuse. i.e Possible thermal shock from low return temps/Flue Gas Condensation. Use a "Tekmar" control to protect it Some pix may help to give some more advise! Richard from Heatmeister.

Gordy

Depends

In my situation I have a WM CGM 7 CI boiler that was installed with bypass piping arrangment into a mix valve. Return temps to the boiler Never get over 95* been runnin that way since 1993 still in great shape.

But here is the thing the boiler is twice as big then needed. With bypass piping the boiler does not get the full 15 GPM flow for the system, maybe only 6 GPM goes through the boiler. So with that said there are a few variables that allow the boiler to function with this arrangement, and not be damaged.

That is no excuse for improper piping for a CI boiler To allow for higher return temps to avoid boiler shock. Myself I'm letting it go to see how long it lasts this way with low return temps. If its life is shortend, oh well that gets me into a Mod/Con quicker, right now its been runnin for 14 years.



Gordy

John_201

It is cast iron for sure.The contractor is correcting the system with a Taco RMB soon. I am concerned about damage/safety to the boiler after running like this for 2 months. It is an in-slab with one zone. He is also kind of balking about adding a LWCO but I think I have plenty of info to convince it is an absolute requirement. You might have seen this mess before. Photos attached

[Deleted User]

Something else is

wrong - if max attainable outlet temp is 120*.

That said. We remove 40 & 50 year old, cold start, cast iron boilers installed w/ NO thermal protection quite often. Not because they're damaged. But, because they're not efficient.

John_201

It is one zone with no primary/secondary loop installed yet so the return temp is only about 100. I've got the control turned to 160 but with the flow and dwell time in the boiler it sits at 120. Zone is about 1450 square feet.

tim smith

Regarding damage

I would say that unless it has cracked and is leaking, no damage has taken place. Condensation issues over that period I would say would be nill. Tim

Derheatmeister

Changes in the industy

Yes i have seen the pix before, and it seems to me that you contractor needs to educate him/her self first then install a system !!!. what i see is ,what we call :" design by solder". if you consider the costs that it takes to install a cast iron boiler and then protect it with the appropriate controls to lower the in floor temp to the proper operating temps and then you also consider the operating cost , it becomes a no brain-er to use a Modcon boiler based on outdoor reset. But change comes very slow with some people. and they are just doing the "safe thing" so they use Cast iron boilers, because that's what they do!...

Al Corelli_2

I STILL Say...

1. Move the pump to the return AT the boiler.

2. OPEN UP that valve that is "behind" the water heater.

3. Throttle the manifold gate valve from the manifold to get the temps in line.

Sure, it isn't as "super nifty" as an RMB, but without killing the contractor (I remember he is new to hydronics), he can make an attempt to get it running correctly.

How many RMBs has he installed? Who is going to program and service it?

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[Deleted User]

al

1. Move the pump to the return AT the boiler.

i'm new also, please explain. is that still considered pumping away from the tank?

John_201

Thanks for the input however I think you must have missed the question, "Is the new boiler damaged?".

1.The original system had a relay controlled mixing valve with outdoor reset that was removed.

2. Valve adjustments you mentioned have been tried but the pump was not moved and nothing happened.

3. Another day of labor to try something that "might" work is not acceptable especially in light of the fact there was another control in place and it was removed.

4. The distributor he is working with has 3 engineers on staff to support him with programming and service issues for the RMB.

Bottom line is we are just trying to get this system back to having the 1950s controls updated and replaced to the 2008 version.

heatboy_3

I love the RMB.......

.... if it used in the correct application. While the RMB will surely make the radiant side of your system proper, it will do nothing to make your boiler safer and/or more efficient.

Since there will be no control of actual boiler operation, you will, most likely, use more fuel than you do now because the higher you run the boiler the more fuel is consumed than at lower water temperatures.

With the RMB, the boiler enable switch is your only boiler control. It doesn't mean the boiler will get above condensing mode. If it does it will just cycle all the way to limit, what ever that may be.

Boiler control needs to be addressed, such as with Tekmar, and the RMB, while a wonderful piece, does nothing for you with regards to that.

John_201

Can you please be more specific on the boiler control side of things please. What controls are need and how/where would they be installed. Many thanks!

Mark Hunt_5

Few years back


I was doing an energy audit in a home that was 7 years old at the time. The owners were on their THIRD boiler.

The house was heated with staple-up radiant and the installing contractor used the aqua-stat on the boiler to control water temps. This he set to 140° max. No mixing device, no primary/secondary piping.

The first boiler lasted 5 years and was replaced with an identicle make and model. That one only made it through one season. The third boiler was from a different manufacturer but for all intents and purposes was the same thing. Cast iron, atmospheric gas fired boiler. That one had yet to see a heating season. The reason given by the installing contractor for the change was that there was a recall on the other boiler model. Absolutely false. The fact is that they could not get a third boiler under warranty and the unit they substituted was cheaper than the original.

In another home I was called to look at a "problem" radiant system, I found that the home of four years old was on it's second boiler. Oil fired this time and again, low temp water system with NO boiler protection and the aqua-stat that came with the boiler was replaced for one with a lower setting, 140°.

I STRONGLY believe that improper combustion AND insufficient draft coupled with no return water protection helped those boilers to an early grave.

Once you get the control strategy straightened out, you would be doing yourself a HUGE favor by making sure that a complete combustion analysis is performed. It assures that the combustion appliance is burning and venting efficiently and more importantly, safely.

Mark H

John_201

I should have been more specific. It is a Taco RMB-1 that will be installed. I went back to the literature and it does indeed have a boiler control operation that looks like it controls the return temperature. Am I missing something?

John_201

I already have. The too small pipe is also threaded which is another no no. Also, there is no sediment trap on the gas line.

The whole near boiler piping has to be redone to install a Taco RMB-1 to get the return temps and supply temps correct. I will pay close attention to any unsupported pipes while they are installing it. I have a substantial list of do overs. Thanks.

Al Corelli_2

Assume...

I would assume that the PONPC would be moved along with the circ.

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Al Corelli_2

Input

1. I know what you had before the install. I did not miss the original question. HAd hoped to save you and your contractor some grief/money. I am well aware of what the RMB is capable of.

2. If you tried to adjust the valve, but did not move the circulator, then nothing would "happen".

I wish you luck in your endeavor to find comfort.

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[Deleted User]

ah assume

something i can't do with my limited knowledge

thanks

Al Corelli_2

Sorry

Sometimes I think slower than I type..


Al

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