Mod-con stainless with cast iron radiators - problem?

JeffGuy

I (finally!) have a plumber lined up and a Burnham Alpine mod-con ready to order. But some of the plumbers I talked to (who tried to talk me out of using an Alpine), made me concerned that I can have heat exchanger failure due to rust or sediment from my 100 year old cast iron pipe and radiators. The fact that the 100% coverage warranty on stainless mod-cons is only 7 years adds to my concern.



Is this a realistic concern? If so, what can be done to solve this - is there any kind of pipe filter or fitting that should be connected to make sure the heat exchanger is protected? The boiler will be connected with primary-secondary piping.



THANKS!

zacmobile

filter

Install a strainer or even better a filter or dirt separator on the system return before the boiler. Also make sure the system is flushed and the appropriate corrosion inhibitor chemicals added.



http://www.caleffi.us/caleffi/en_US/Site/Products/Product_news/args/detail/~Details~News~news_detail_0000243/type/newshome/index.sdo

JeffGuy

Thanks

Thanks for the link. But YIKES is there a cheaper alternative? I have an old gravity system with lots of water and 3" output and 2" return pipes. That will be re-piped with near boiler pipes to a smaller size, but even the 1-1/2" brass dirt separator is $440 (the 2" steel one is $2000 to more than $3000!)



What are the best and most cost-effective choices?

bob eck

Mod-con & old cast iron radiators

Take a look at any of the mod-con boilers and all the heat exchanger warranties are almost the same.

I have a Triangle Tube Prestige Excellence PE110 in my house with old cast iron radiators. When I took out the old oil boiler the water that came out of my system was not real bad looking so I did not add any chemicals. 

Have your contractor flush out the pipe and radiators and look at what the water looks like when coming back out. There are chemicals that can be added to the system to prevent corrosion. Check with the boiler manufacturer and see what type of chemicals that are safe to add to the system that will prevent corrosion and still not hurt the heat exchanger.

Some mod-con boiler heat exchangers have very small passages be very careful what unit you go with. The Triangle Tube boiler heat exchanger is very good and there are more mod-con boiler companies starting to use a heat exchanger just like the Triangle Tube heat exchanger

Are you going from oil to nat gas?

Good luck with you new boiler.

zacmobile

ease of service

Do you know what the heat loss is of your house? Gravity systems had large pipes to allow natural convection in the system, it will now be pumped so the boiler piping connected to your existing system will be much smaller, depending on the heat requirements of your house and the flow requirements of the system you would most likely end up with 1-1/4" or even 1" piping. Like I mentioned before dirt separators are the ultimate but a wye strainer will do the trick too, the only difference is servicing: with the dirt separator you just have to crack the drain valve to dump the sludge, with the strainer you would have to shut the system down and pull the screen out. The harder the task is to do, the least likely it is to get done, I think the dirt separator would be well worth the money.

CMadatMe

Hydro Seperator

Tell them not to primary secondary pipe and use a hydro separator (low loss header). It will protect the hx, allow you to blow off any sediment that falls to the bottom of it, promote colder return water temps. Also takes away the need to add a spirovent if the proper LLH is chosen. While a LLH cost is more, saves labor and the need to add a spirovent or similar air elimination.



http://spirotherm.com/quad/

Gordy

Why not use

A hydraulic separator instead. The alpine requires primary secondary piping any way because of its small HX passage ways. Unlike the new Dunkirk, TT etc boilers



For the money of a dirt seperator you can get a hydraulic seperator that does dirt seperation, Air removal, and primary secondary piping with less work all in one unit. Caleffi, and others make them also.



Sorry Chris reply while you did .......Great minds must think a like.

CMadatMe

Great Minds

Think alike Gordy.

CMadatMe

Bob

Triangle fired the Polish company that was making the hx for them and found a new supplier. The current hx has differences in it. The polish company then went out to Lochinvar and NTI. While they are similar in design not exactly the same. Triangle is now all 439 Stainless and the passages beefier.

JeffGuy

OK, hydraulic separator

If I use one of these (and if I clean it out occasionally), that will cover me? If so, I'm convinced. Normally I would go the cheap route (strainer plus scoop plus Tees), but I can see the advantage of making it as easy as possible to do the maintenance - I'm afraid I'm not big on maintenance so the easier the more likely I am to do it.



The next issue is whether the 1-1/4 pipe size hydraulic separators they make will handle sufficient flow. The Taco (about $350) is rated for a max of 15 GPM; the Caleffi (about $550) is rated for a max of 18 GPM. The Alpine 210 specs 1-1/4 inch pipe and a primary pump with a flow of 15.5 GPM at 25deg; or max of 19.4 GPM at 20deg.



Would these be considered within spec, or do I need to go with a larger size?

Gordy

Right size

Boiler?  Was a heatloss done? EDR measured?  Swapping a new boiler using old boiler size is a no no. Structures r value may have changed, and fuel was cheap back in the day of gravity systems.  No one complained about to much heat.



Gordy



 

CMadatMe

LLH Size

The minimum near boiler piping of the ALP210 is 1-1/4". The recommended delta-t is 25 degrees. Boiler pump would be a Grundfoss UP26-99FC (Speed 1) or Taco 0014. You need to move 15.5gpm. The following LLHs will do the job. Taco HSEP125, Caleffi 548097A, or a SpiroTherm Quad.

Paul Pollets

Clean the system!!

It's very easy to clean the system piping and radiators using proper boiler cleaning chemicals before removing the old boiler or with the new appliance, as long as you can isolate the new boiler. Much cheaper than a large strainer, and it will work better.

icesailor

Mod-Cons, Gravity and pumping (FWIW)

I just did a job that is like what you are doing, in a sense.  Consider this.

I was doing some plumbing in an old house and it had an old gravity system on two floors with a 4" supply and return. Someone had installed a Peerless Mooring Block for a boiler and added an indirect. They connected the boiler to the supply with 1 1/4" copper and the return was the same. On the return, they installed a Taco 010 40 GPM pump. The indirect was a Taco 007. The house would overheat like crazy with little control. Most of the radiators on the second floor were disconnected in the cellar with the pipes still there. I left the 010 circulator and made it a primary heat loop. I installed two closely spaced tees and a Wilo Star 21 3 speed pump for the secondary loop, connected to a Taco "I" Series, 4 way mixer. The valve gives you outdoor reset and boiler protection. A dip switch controls whether it is 120 degree or 140 degree boiler water. The 4-way kept the flow in the secondary loop even and within 20 minutes of turning it on, all the returns were warm and I had a 20 degree Delta T.

The Taco I series 4 way is an awesome way to deal with high mass systems and low mass boilers. I love hydraulic separators but this really impressed me.

The owner wasn't in anyway going to go for a new boiler and a complete change of his heating system. He likes his old radiators in hos old antique house.

If you just P/S a high mass system with a low mass boiler, you can't really control the flow in the system. This way, you can. It doesn't matter that the primary system is grossly over pumped, It works fine on medium speed and would probably work as well on low speed. But its something to consider. 

JeffGuy

I don't know enough

I have no clue how this part would be used, nor could I find a data sheet on it. Maybe I could understand with a diagram?

JeffGuy

Cleaning?

Could you tell me what you recommend for cleaning? Is it possible to clean it once the old boiler is removed - I ordered my new boiler today and was going to drain the old one tonight or tomorrow to be ready to remove it this weekend?

JeffGuy

EDR

Thanks, I did a heat loss, but didn't measure EDR (that means counting radiators and sizes right?). I put this in another thread, but the heat loss using Slantfin Hydronic Explorer came in at 160,000 using indoor temp of 68, or 165,000 using indoor temp of 70. I think I was pushing it (overestimating insulation in walls). For a house as old as mine - 100 years - it is hard to estimate what to use for insulation factors unless you have done major demolition which I haven't.



I guess I need to do an EDR to figure out how much radiation I need with baseboard to match the radiators in the rest of the house - but it seemed to me it didn't matter that much as long as the zones were kept separate (which they will be, though they aren't now). But that's the topic of my other post (sorry but I haven't kept these separate like I intended to!)

Gordy

Good Reading

 A good article Steamhead wrote on gravity conversions, and circulator sizing. It may become helpful to you.



Sizing Circulators for Hot Water Heating Systems



Gordy