We want to replace the boiler in our basement and have been given conflicting advice about what to get. We have an old house, built 1903, and have hot water radiators. We have already done extensive renovations and our contractor told us we should get a high efficiency combi gas boiler for both heating and hot water.

However, another plumber told us that we should stick with a standard boiler and hot water tank like we have now because the new boilers don't work well with old houses and apparently silt can get stuck in the pipes. Our contractor's plumber said thats not true and we can just put on a filter.

Also, we had also wanted to relocate the new boiler to the side of the basement rather than the center where it is now. The "other" plumber said that the boiler should remain central so the water can be evenly distributed through the pipes. Contractors plumber says thats nonsense because there are pumps.

Who's right??

  • Is a hydraulic separator being included with this new boiler install already? Commented Jan 30, 2021 at 20:45
  • @ThreePhaseEel. I’m not sure what that is but I assume no. The whole system is very old, from the 1950s and we haven’t done anything to it yet
    – Charlie
    Commented Jan 30, 2021 at 23:16

1 Answer 1


Fit the new boiler where you want.

As part of the job get the plumber to flush the pipes to remove silt.

The boiler does not have to be central - the pump provides the push for the water and heating circuits have balance valves to control the flow or they can be fitted.

But consider if the existing boiler still works, how long is the cost of fitting going to need before it is paid back by the increased efficiency?

  • Thanks for your answer. We want to replace the boiler because the current one is very old (1950s) and we’ve had a couple of issues so it’s time to replace it. Also, we’re doing this as part of a basement reno and we need to replace a bunch of piping. Do you have any opinion on whether one of those high efficiency combi units will be suitable for an old house?
    – Charlie
    Commented Jan 30, 2021 at 23:55

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