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repiping a hot water heat system--mixed info

Kelly_2 Member Posts: 7
> We have an old house (1923) heated by hot water <BR>
> radiators with a fairly new (5yrs) dunkirk <BR>
> boiler. The pipes are all over the basement--a <BR>
> two-pipe system, I think? We want to move the <BR>
> pipes to hide them. We have been quoted to do the <BR>
> job by replacing all the piping with Pex--with <BR>
> each radiator on an individual circuit from a <BR>
> manifold, but also been told that this cant be <BR>
> done--pex diameter is too small and the job must <BR>
> be done in copper. Who do I believe!? <BR>


  • Kelly_2
    Kelly_2 Member Posts: 7
    Repiping hot water heat system--mixed info

    We have an old house (1923) heated by hot water radiators with a fairly new (5yrs) dunkirk boiler. The pipes are all over the basement--a two-pipe system, I think? We want to move the pipes to hide them. We have been quoted to do the job by replacing all the piping with Pex--with each radiator on an individual circuit from a manifold, but also been told that this cant be done--pex diameter is too small and the job must be done in copper. Who do I believe!?

  • Provided the length of the runs are kept within reason, ½" PEX can adequately supply all but largest iron radiators. Unless this is a true mansion, you're highly unlikely to have a radiator of such size.

    Since you're re-piping, NOW is the time to install thermostatic radiator valves (TRVs)! Labor will be kept to a minimum.
  • Kelly_2
    Kelly_2 Member Posts: 7
    how hard is this job?

    So when I started trying to find a contractor to do this job, it was 90 out. Now it is cold. I have one bid, and it was 10 days late. This job needs done. I gather from one guy that his reluctance is that pulling all that old pipe is a dirty tedious job.Or maybe the folks I have talked to already have all the work they can handle. So is this a job a reasonably competent person who doesn't mind dirty and tedious can do? We have tackled lots of jobs that required learning a lot to do.
    Is the manifold configuration preferable to the two-pipe configuration? Can the two-pipe be done in PEX? And what is a reasonable run? the boiler is in the southeast corner, and the furthest radiator is in the northwest corner--~45 feet. Is that too long? And where is a good source for the valves? they sound like a great addition. Also, can someone recommend a particular type and manufacturer of PEX-- my reading has led me to believe that most dissatifaction with the material are from poor choice of material or connector. Is there a resource anyone can recommend to get educated on this job?
    And if it is a bad idea to try and do this ourselves, know anybody good in Salt lake city?
  • jerry scharf_3
    jerry scharf_3 Member Posts: 419


    I think Mike's point about adding TRVs is excellent. You will be very pleased with how comfortable the rooms in the house will be. Danfoss, Honeywell and Myson are 3 manufacturers and there are others.

    To go to TRVs requires changes to the piping and controls of the boiler (constatnt circulation, pressure bypass, P/S plumbing for the boiler.) So I would recommend that you have a pro do all that work. If you want to save some money, perhaps you could work out a deal where you tag the existing pipes per the installer's desire, cut out the rest of the old pipe and label/run the PEX from the boiler location to the ends. This way the installer does the stuff where his skill is maximized, and you do the other stuff.

    It's biting off more than just replacing pipes, but it is well worth is. Should you ever decide you want to go with a more efficient boiler, that change becomes a snap if the near boiler piping is done correctly.

  • Kelly_2
    Kelly_2 Member Posts: 7

    this sounds like a great idea. money is part of the issue, the other is just being used to doing things myself, and that the pros seem aweful busy, and if the job is shorter, maybe I will have an easier time getting bids. (several folks have looked, said bids would be forthcoming, but its been a while). Can anyone suggest someone out here? (another problem--the phone book is not the best reference)
  • Kelly_2
    Kelly_2 Member Posts: 7
    more efficient boiler

    So my boiler is a 5 yr old dunkirk. Is it not very efficient? (Installed before we bought the place). We are doing this stuff now, so a good time to think about it-- especially with fuel prices as they are. Can you reccommend a better choice? What would that kind of thing run
  • Kelly

    Please do not take offense at the following as none is intended.

    You are looking at things completely backwards.

    Your heating system is about comfort and efficiency. Regardless of when it was installed or designed, those goals were at least part of the equation.

    You want to renovate your heating system based solely on aesthetics because you don't like pipes in your basement!

    If you're willing to spend the kind of money required to do such and still have a reasonably comfortable and efficient system you are truly foolish to not do what really matters--make your system supremely comfortable and exceptionally efficient.

    Any changes to your heating system should FIRST consider comfort and efficiency. Aesthetics should come LAST!

    Being part artist I do understand. The custom "bronzed" rads (my own formula which I freely share) in my house are works of FUNCTIONAL art.

    I did move some pipes in my basement to get them out of the way, but they're STILL in the ways of the "dead men".

  • Kelly_2
    Kelly_2 Member Posts: 7
    none taken

    fair enough, Mike, and no offense taken. I am trying to consider the comfort and effiency as well, but I guess i hadnt thought it uncomfortable, and I am asking about effiency, because I agree, if Im gonna move pipes just to get them out of the way, i should do what I can to improve the system.I think the TRVs sound awesome, but the only complaint I have had about my system is that it is slow to warm. I have been given to understand that that is just the tradeoff for the comfort of hot water heat. And this is the only hot water heat system I have ever lived with, or even known, so I have nothing to compare it with. So please, forgive my ignorance and I would truely appreciate whatever you can tell me about what I can do to the system to improve it.

  • Particularly if your system is a gravity conversion (the pipes in the basement will be VERY large and probably two pairs), the mass is quite high and they do take considerable time to heat from a cold state.

    One of the beauties of a system with TRVs is that the water will be constantly circulating and heated. This GREATLY speeds response. You may think it wasteful to keep the water constantly moving and heated, but nearly all such systems also incorporate reset in some form. Reset will keep the water heated only to the level required in the current weather. Should the outside temp rise to the point that heat is no longer required, the circulation and heating will stop.

    The system can certainly be re-piped. This will however be quite expensive and potentially quite disruptive. Depending on the layout of the system, it can also be rather difficult to balance requiring "flow setter" valves for each radiator. TRVs eliminate the need for such valves and produce a self-balancing system.

    Hot water systems with standing iron radiators have always been known for good comfort. Most however used to be fueled with solid coal. By watching the weather, tending the fire and adjusting the draft, they produced a crude version of a constantly circulating system with outdoor reset. Once they were converted to gas or oil and controlled by a simple on-off thermostat, they lost this ability. Unfortunately this caused some inefficiencies that did not previously exist. Also, boilers are routinely oversized by a huge amount and because most cannot vary their fire, yet more inefficiencies appeared.

    Combine TRVs and a condensing/modulating boiler in an old system such as yours and it will honestly be better than new. The original proportional function is restored yet it now truly automatic and almost infinitely adjustable.

    The experience of big iron radiators constantly staying just warm enough to heat the space must be experienced to be believed. You're likely to find that you are more comfortable at lower temperatures than you thought possible. Each and every room can be kept at a temperature suitable to the activity in that room. Unused spaces can be deeply set back, but will re-heat with surprising speed when called to do so.

    Your fuel bills will likely plummet just as your comfort rises.

    If you at all have the budget, please consider such a renovation to coincide with the re-piping. You will be extremely pleased for a very long time.

    p.s. Even before you re-pipe, your first job should be to insulate/weatherize as much as practical given the structure.

  • Kelly_2
    Kelly_2 Member Posts: 7

    thanks, Mike, so it sound like I will get increases in effiency as well as less head bumping by changing the pipes--it is a gravity conversion. As far as disruption- we are tearing out and rebuilding everything down there as part of this, and weatherizing to boot, so great.
    I really appreciate your help-- it has given me the background and vocabulary to talk to the pros (several have looked quite blank at the mention of TRVs, I guess they arent that common here).I really hate having to do things twice, so I would rather get it right the first time.
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