Will gas boiler will blow up?

Catherine

We have one furnace in what is now a two apartment house. The building was built as a single family house in the early 20th century.There was only one zone and one thermostat. There is no practical way to separate the floors; one apartment or the other was always too hot, or too cold.We have added a heat pump for AC and heat on the top floor. We only want to cap and remove the radiators on that floor. We were told we have to remove ALL of them in the building and scrap the furnace, because the furnace has too much pressure and will blow up if we use it for half the radiators it was sized for. What do you think?

jason2018

Fear tactics. Having said that the boiler will most likely now be oversized and life expectancy of boiler reduced if the situation you talk of were to take place, I’m assuming it’s an 80 percent efficiency boiler with no modulation features.

ChrisJ

What area are you located in @Catherine ? Heat pumps alone won't cut it where it actually gets cold.


And no, the boiler won't explode assuming the controls are working the way they should be.

Jamie Hall

Hot water, I presume? But in any case, as @jason2018 said, scare tactics. That applies whether it's steam or water.

Not to put too fine a point on it, whoever told you that is at best sadly misinformed and at worst a flat out crook looking to take your money.

Now... having said that, there are two reasons that I can see why you want to remove the radiators on the upper floor: perhaps they are in the way. OK, fair enough. Or perhaps you have been told that doing so will save money. Not OK. Depending on where you are, you might. On the other hand, you might find that the heat pump just couldn't hack it on the colder days and you wish you had them back. If this is hot water heat, there is no reason why a vaguely competent heating person -- even a vaguely competent plumber -- couldn't zone the system so that you could still use them when you wanted to. If this is steam, it's a little harder, but both one pipe and two pipe steam can be fitted with thermostatic vents (one pipe) or valves (two pipe) to control the heat from the radiators.

Your boiler will be oversized, either way. If it is hot water, you can minimize the impact of that by setting it to deliver the water at a lower temperature. If it is steam, you're stuck on that. However, in either case neither the efficiency of the boiler nor the life will be reduced all that much.

HVACNUT

If yours is a water boiler, not steam.


If your plans are for A/C regardless for the 2nd floor, you can have a hydronic coil installed in the ductwork and zone it that way. It shouldn't be impossible to run a pex loop and thermostat wire from the boiler room to the attic (I assume) air handler. Wire in an isolation relay, and done.
The system will need a glycol mix to prevent the water from freezing in the attic, AND an emergency drain pan under the A/H and hydro coil with a wet switch to shut the system down in the event of a water leak.


You can still get a high efficiency heat pump and stage the 2nd floor heat.


If it's a water boiler, can you see the piping arrangement in the basement. Do 2 smaller pipes branch off from a larger pipe to each individual radiator?
Where the smaller pipes branch off, does the "Tee" fitting have arrows on it?
This is called a Monoflo system.

If so, the branches feeding the 2nd floor cannot be just cut and capped. They must be piped back into each other.

Some pics of the boiler and piping will help.

Catherine

Thank you all for your help!
We are Richmond, Virginia, 7a. The building is a solid brick two story, plus basement, The ceilings are 10' on first floor, 9' on second. The exterior brick walls are plastered directly on brick. It was a single family house, 1000+/- square feet on a floor, approximately 3000', including the uninsulated basement.
The system has a gas-fired furnace, with hot water radiator, the big cast iron ones. They do take up a lot of room. I wonder if it is possible to remove just the ones in the way, maybe leave on in hall and bath.
I will take pictures of the furnace, which replaced the oil one, fifteen years ago. I will try to figure out whether it is a one pipe or two pipe system.

Gordy

First you need a competent hot water heating contractor. Just removing random radiators with out properly repiping the ones left could be a disaster.

Jamie Hall

Gordy said:

First you need a competent hot water heating contractor. Just removing random radiators with out properly repiping the ones left could be a disaster.

But not in the way of blowing up. That it won't do, unless you disable the safety devices. What @Gordy means is that it might not heat well -- if at all.

Steamhead

It should be possible to balance that system. Any pros around Richmond on here?