Joined on January 19, 2012
Last Post on August 31, 2014
@ February 5, 2013 6:59 PM in boiler sizingI would absolutely do more than one boiler. You will get excellent turn down ratio and redundancy. I single boiler will short cycle like crazy.
You should be able to size the boiler(s) to the heat loss. The issue you are going to run into is that your rad slabs and your air handlers can suck energy faster than you can make it. When the big slabs come on line they will drag down the system temps and cause the handlers to blow cold air. Check out this http://www.radiantandhydronics.com/Articles/Glitch_and_Fix/BNP_GUID_9-5-2006_A_10000000000001216751
Even if all 4 handlers come on at the same time the temps will drop.
I would consider twin 150k to 175k or even 3 110k. I would use a control strategy that prevents the slabs from hogging all the BTU's at startup. The air handlers may need to be rethought. Why 100K? They should be sized for the load as well. Ideally the coils should be sized for the low temps the mod/con loves.
@ February 5, 2013 6:42 PM in I'm posting this for Bill Brooks.The first part of your post reads like an air problem. Aerated water is put in in the summer and left to deaerate where you least desire.
The horror of horror of the cold supply manifold temp smells of a bad or non existent check valve. Is it possible that under certain circumstances, one of your zone circs is pulling water backwards threw a another zone(cold slab)?
I would start by just feeling the supply and return pipes during different operating conditions. I bet there are times when things that are supposed to be hot are cold and vise versa.
@ February 5, 2013 12:09 AM in How Would I Disconnect this Radiator?You won't get anywhere turning the bushing. You have no choice but to cut the pipe. A hack saw would be the cheapest way to do that.
@ February 4, 2013 5:09 PM in Hot water off steam boiler controlsThe pressuretrol and the hot water aquastat are both switches. If either of them want more heat the will tell the boiler to fire. Your steam system will not heat at all with 180 degree water, so with both systems calling you get 212 at the boiler. If you want to cool down the hot water system during the steam call you will have to either slow the flow to the exchanger or add a mixing assembly.
@ February 4, 2013 4:53 PM in Will an indirect work for me?What size is your boiler?
There are 2 factors, storage and heat exchanger size.On one hand you don't need much storage as your boiler seems to be able to handle your needs on demand. Using this approach you could size the exchanger a bit bigger than your boiler and you would be all set.
The other thing to consider is that your existing boiler is likely oversized for your heating needs. When you do upgrade your boiler It will likely be smaller. With a smaller boiler you will need more storage and less exchanger..
If you post your boiler BTU rating along with the building footage type of construction and area of the country we should be able to take a guess at a good long term plan.
Be weary of the ratings of indirects. They assume a certain boiler output and cold water temp. They may or may not apply
@ February 4, 2013 1:11 PM in Understanding Primary/Secondary Piping -ModConI think you are getting hung up on this flow rate thing. What it really comes down to is BTU's.
Your 65 feet of baseboards will distribute about 600 btu/foot with 180 water and 150 btu/foot with 110 degree water. That's 39,000 BTU/hour to 9,750 BTU/hour depending on how you set up your heat curves.
Now look at the output ratings on the boilers.The 2 SWEI suggested have minimum outputs of about 8,100 and 9,900. That looks like a pretty good match.
Select a boiler then decide how to pipe it. Gavonni(sp) exchangers like the cadet are finicky about flow rates, they must be piped primary /secondary. Fire tube exchangers like the TT and many of the Lochinvars can often be piped direct.
The bigger question for your design is DHW. You will not be happy with a 40k btu instantaneous. A smaller boiler will require some DHW storage. GPM X 500 X delta T = BTU/Hour.
Hope that helps,
@ February 4, 2013 8:25 AM in New Thermostat 3 Wire Hot Water Boiler SystemWhere do the wires go on the other end? It sounds like you have a 2 stage t-stat but it could be something else.
@ February 4, 2013 8:22 AM in Hot water off steam boiler controlsIt sounds like your steam system is controlled by a pressuretrol as it should be. That system will boil water (212 degrees) until the set steam pressure is reached. The hot water side only needs 180 degree water. When only the hot water side is calling there is no need for steam so the aquastat turns it off at 180.
@ February 3, 2013 4:21 PM in Will an indirect work for me?An indirect would work great for you. If you have the BTU's to run a tankless you can absolutely do an indirect. The indirect will also work in the future whenever you upgrade your boiler.
If you plan on keeping your existing boiler for a long period of time you can use your existing tankless coil with an electric water heater for storage (no electric hooked up). Icesailor has posted a proven detail for this.
@ February 3, 2013 4:06 PM in Please define short-cycleThe generally excepted number is more than 6 cycles per hour equals short cycling. With modulating boilers I think we should be shooting for longer cycles than that.
@ February 2, 2013 10:24 AM in Triangle tube prestige mod con?The TT boiler is fantastic. They developed the heat exchanger that is now used by Lochinvar and others (I think the dunkirk is different). They then upgraded it a bit when they switched suppliers.They trimax controllers are very intuitive and the boiler requires little maintenance. I don't think the TT and Buderus are even in the same category. I don't like aluminum exchangers and the GB series have had more than there share of "glitches". Buderus support is still in denial.
@ January 31, 2013 11:59 AM in Linking Cut Pipe Ends?Check your other post. I gets confusing when you post in two places.
@ January 31, 2013 12:27 AM in Better balance, better heat... starting from scratch? (a LONG post.)I see you have your system posted twice. I think this one gives more details of your system. As Ice and SWEI pointed out you are piped direct return not reverse return. The water is lazy, it just keeps taking shortcuts. With reverse return the water has to travel the same distance to get to every radiator. This naturally balances the system. To convert yours to reverse return, you would run a new supply or return from the boiler to the end that is presently capped. The existing supply or return would be capped at the boiler end. You need to reverse the direction of flow in the main on either the supply or the return.
Pex with o2 barrier would be suitable for the run. I would still use iron or copper near the boiler.
It would be best to pump away from the expansion tank.
With iron radiators and a boiler almost 30 years old I would consider a Mod/Con boiler with outdoor reset. The boiler owes you nothing and those radiators would work great at lower temps. I would expect savings of 30-40%. If you are going to put the work into the repipe why not save some money. I am a huge fan of Triangle Tube boilers. I would recommend any boiler with a fire tube exchanger.
Thank you for the thorough post. I hope this explanation helps.
@ January 29, 2013 10:59 PM in Ghost flow where we don't want itWhat Steve is proposing is parallel loops that all pull through the boiler. Since cast iron boilers don't need very high flows it should work just fine. I would suggest some sort od low temp protection on the radiant slab. Unless the slab is quite small I think it will return cold water which will cause the boiler to condense.
@ January 29, 2013 6:08 PM in Ceiling Radiant HeatI am not a fan of electric radiant in drywall. I remodeled an entire house and switched to hydronic. I really could not believe they got a UL rating.
The system consists of bare electrical conductors imbedded in drywall. The system was energized all the time because the t-stats only switched one leg. There were areas where a slight roof leak had turned the drywall to kitty litter. There was just a bare live wire laying in kitty litter looking for something to arc to.
The panels were clipped together with little plastic connectors which were not accessible.
An electrician could test the amp draw and resistance to get some idea of the health of the panels.
I personally would not live in a home with electric rad ceilings.
@ January 28, 2013 2:02 PM in Moving Threads?Dan,
Is it possible for an original poster to move a thread to another category?
It seems many threads start out on "The Wall" or another category and it is soon apparent that it belongs somewhere else. I was wondering how big of a tech headache it would be to make that possible.
@ January 26, 2013 10:34 PM in ModCon Icing on ChimneyI was thinking the purpose of this forum is to insure proper, safe installations. I don't see any on this post. Non meet manufactures specs. as Henry pointed out. I also don't see a whole lot of common sense. Insect screens, proper separation, approved terminations?
What happens when the roof termination ices up? The fan will push the gas somewhere. How about a bird nest or a kids toy (or rocks) in the side wall picture.
Let's all promote proper safe workmanship not "it otta work".
@ January 26, 2013 10:13 PM in Max Heater Delta T - Help me understand.Does the problem occur when one load is present or only when both call?
It reminded me of this http://www.radiantandhydronics.com/Articles/Glitch_and_Fix/BNP_GUID_9-5-2006_A_10000000000001216751
@ January 26, 2013 3:31 PM in ModCon Icing on ChimneyDo you know the difference between God and a Pilot?
God doesn't think he can fly a plane!
It is condensate and it can plug up the cap. I have seen it and it makes a mess. There is not a manufacture on the planet that would sign off on this detail.
I respectfully disagree
@ January 26, 2013 10:53 AM in ModCon Icing on ChimneyWhy not just drill a hole in the cap, run the pipe through and put a coupler and a screen on top?
I think the condensate could build enough ice to block the termination. What then?Is it worth taking the chance?
Do you really want all that vapor condensing on the cap and dripping down the clay pipe?
@ January 24, 2013 11:25 PM in Zone short cycles and t stat reads lower than settingDo you have zone valves or circulators?
Can you post a picture?