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How to UPGRADE old heating system with modern technology

I live in a old 1930"s story and a half with my wife two grown kids and our grandson. We need to inlarge our bathroom and kitchen so we thought about removing the radiators by installing the heat in floor in those two rooms.Do you have any ideas for me:confused: that would allow this type of system to work along with my same heating system, and if so could I down size all of the lines to the other radiaters. I have most all the walls opened up now so any advise this do it yourselfer could get would make my family very happy which in turn would make my life, well very nice. Thank you very much...Monte (P.S. Hope I posted in the right place if not my apologies.):D:D:D:D:D

Re: How to UPGRADE old heating system with modern technology

Radiant heat requires a lower water temperature then what is required for your radiators. It can be done but it won't be cheep.
Do a search on the subject and you will find all the information you need.


Re: How to UPGRADE old heating system with modern technology

if your looking to install radiant in only two small rooms such as those you will find it much much cheaper and easier to have an electrician install a heating coil in the floor..

its far easier to have a sparky run a couple 220 wires to these spaces than it would be for a plumber. the plumber would open up far my wall space so to get his pipes in the walls and floor system

also, trying to upgrade an existing old heating system wouldnt really work, most plumbers/ heating contractors wouldnt be able to guarentee that an old boiler will be able to handle the extra demand. most homes i work on get radiat in floor but they also upgrade the heating system.. though it will be more money up front a new furnace will be more efficient for your house than the old one. now what's being spec'd is to have a furnace that operates continoully but not as hard.. older ones would use more energy by coming on every time the temperature drops and then plays catch up.. burning more oil

Re: How to UPGRADE old heating system with modern technology

GUYS my boiler is but ten years old could i down size my delivery lines and or run a sort of valve system that would deliver only to the radiaters that called for heat or seperate the rooms with aditional pumps? I have all my piping exposed now so i believe that for me now is the time to do what ever changes that need to be done. any ideas? thank you! monte:D

Re: How to UPGRADE old heating system with modern technology


Thank you for your interest in hydronic/hot water heating.

There are many ways to modify hydronic heating piping, and many of them can be done by the DIYr if you are able to solder copper tubing (assuming you have copper distribution pipes), or connect PEX tubing with its convectors and other components; the other option, of course, is to consult the Yellow Pages under "Heating Contractors" to have a hydronic technician do the install; most fuel oil dealers also have skilled techs who can easily install what you need.

You mention in your post "downsizing the delivery lines"---these are usually 3/4" or 1/2" copper or PEX supply/return lines at the convectors, and 1 1/4" to 1 1/2 " supply lines near the boiler; their diameters never should be changed; sometimes Thermostatic Radiator Valves (TRVs) are connected to the rads or baseboard to control the heat output of these components, but this would require that you have a piping system that is NOT a SINGLE PIPE distribution arrangement where the piping goes directly from one radiator to the next (see link below); Which type of piping system do you have, Monte?????

Actually, even with a SINGLE PIPE system, the nearby piping around the rad or baseboard can be modified so that a TRV can be used even in these cases.

There is also the need to do at least a perfunctory HEAT LOSS CALCULATION to determine how much heat the new kitchen and bathroom areas will need so they are warm & comfortable on a wintry day---this is especially true for the bathroom; you will find a simple HLC at the site below ; this would take into account your location, amount of wall insulation, the # of windows in the kitchen or bathroom, ceiling height, etc.; many bathrooms in cold parts of the U.S., which would include SW Minnesota, need between 35 to 50 BTU/sq.ft. to remain comfortable on wintry days; thus, if your bathroom is 100 sq.ft. with 8' ceilings, you may need 100 sq,ft, X 50 = 5000 BTU/hour to keep it warm----- kickspace heaters have their output ratings stamped on the housing; trying to calculate sub-floor heating pipe could be more complicated---it's another good argument to put the bathroom circuit on its own separate zone valve with a dedicated t-stat for the bathroom.

This topic has already been largely covered in a post entitled "Combining radiant and baseboard", submitted to these boards on 7/26/11---click onto the 2nd link at the bottom of this page to access that post---you should find much relevant info in the threads that will be relevant to your situation.

Speaking to your particular situation, since you have much of the heating piping exposed, you can remove the radiators and any other bulky convectors (you would have to shut off the water supply to the boiler, shut off the boiler electrical switch, & drain the pipes in the bathroom of all water) and replace them with some form of hydronic under-floor radiant heat, or combine under-floor piping with small convectors, such as a hydronic fan-driven kick-space heater for the bath, which is only 4" high X 14" long and usually fits into the base of a vanity cabinet, or is inset into the base of a wall cavity----there are pictures and links concerning these components at the above site listed.

Also follow the links for "A Plain Vanilla System" by Vince Gallipoli that uses 180 degree water to install a sub-floor radiant piping system in the bathroom; also note the Siegenthaler link for using a Taco 571 zone valve to create a separate zone for the bathroom heating circuit---some circuits use a 3-way mixing valve, others just use the zone valve with a separate t-stat to give heat control for the bathroom area.

Ordinarily, two or three separate zone valves are installed in a multi-floor house such as the one you describe in your post so that separate heating control via separate t-stats for the bathroom, the main living area, and the upstairs bedrooms, etc., can be obtained---the zone valves are cut into the near-boiler piping at the main supply pipe & are wired with separate t-stats so that a call for heat can be controlled from any part of the house---the two or three separate zone valve route is usually strongly recommended as the way to go in the type of house you describe; it affords control of the heat & comfort for the bedrooms, bathroom & the heat in these parts of the house can be turned down when not in use---thus, there is usually a good fuel savings return on this type of investment that will save enough fuel over the coming years for the installation cost to pay for itself.

Installing a zone valve bathroom circuit is within the skills of many DIYrs who have soldering skills, & has the advantage of simplicity, over the more complicated & involved sub-floor bathroom heating circuits as noted in the Sieganthaler article "A little floor warming please".

To simplify things even more, it should be possible to simply snake the 1/2" or 3/4' copper supply or PEX supply & return piping when the radiators are removed to the sub-floor area & wrap them in pink insulation to protect the flooring from too much heat as a way to adequately heat the bathroom area.

The counterman at the heating supply stores (not HD/Lowes) in your area (Yellow Pages: "Heating Equipment & Supplies") will usually sit down with you to draw up a diagram of your heating pipe distribution arrangement & advise you of the way the components should be installed; most heating supply houses that once catered strictly to heating techs, will now sell to anyone, often at reduced prices, or even at wholesale; you can also Google such phrases as "Installing a hydronic zone valve" or "Installing a Taco 571 Zone Valve" to get more info.---feel free to click onto my name & send me a PM if I can be of further assistance in this regard.


Re: How to UPGRADE old heating system with modern technology

You really should find a contractor that will work with you on this type of project. This is not a DYI project.

While you may be able to solder, there are many other issues that have to be looked at. For instance, by installing radiant in those rooms you just lowered the load. Your opening the walls so I'm sure your properly insulating. You've lowered the heat loss.

Now you may end up with an oversized, short cycling boiler which will need to be addressed. This type of retrofit is not a matter of just adding a mixing vlv, pump and tubing in the floor and you have a radiant system.

If I caught one my my counter people in any of our 20 plus branches sitting with a homeowner providing what Nasuha described he wouldn't be in the next day. I'm not saying not to help but to help responsibly. The responsible help is to help you find a contractor that will work and consult with you. There are plenty of good contractors that don't have a problem with you providing the labor to install the tubing and some of the other DYI tasks but you need him to help in develping your plan and execution.

I have to disagree with the 35 to 50 btus sqft provided to you. No way. Have done thousands of heat losses, radiant designs and installations since 1989 in zero degree climates and have never seen those numbers in any of my heat losses and designs.

If you want professional advice from the best leading hydronic heating installers, designers and energy professionals across the country visit


The bitter taste of a poorly installed system last longer than the sweet taste of the lowest price.

Re: How to UPGRADE old heating system with modern technology

LOL, here we go again. HVHEHCCA with his mindless, hateful diatribes is back with us again with nothing better to do but spread his venom against his fellow board participants, all in his own myopic self-interest, the interest of industry anti-diy elements; all flying right in the face of the Ask This Old House concepts of helping the DIYr make informed decisions on home construction projects.

Nashua once again has provided an enlightened, balanced approach to the issues presented, and clearly indicated to the OP at the beginning of the response that the option was there to consult licensed contractors as an alternative to the diy route.

I completely agree with the comments and statements made by Nashua, and appreciate his experienced insight into HVAC issues that have helped so many on these boards over the years-----keep them coming Nashua!

I completely DISAGREE with the empty utterances of HVHEHCCA.

Excuse Me

Where in my post did I say I was against a DYI'er? I believe I said the responsible advice as did Nashua was to work with a contractor.

What empty utterances are you referrring to? There is nothing in my post that isn't fact. I believe Nashua would be in total agreement that the heat loss of this structure is going to be reduced. Which will cause the current boiler to be oversized and subject to short cycling. It is something that would need to be looked at and addressed if necessary. Do you feel that a DYI is qualified and has the knowledge to evaluate this and implement the correct solution? Sorry, but I don't.

My reference to there is more to the picture than just installing tubing, a mixing valve and a pump is sound advice. I could write in this post the sky is blue and you would disagree.

Re: How to UPGRADE old heating system with modern technology

Get these mutts away from me!

Why, oh why is hvhehcca so soft in the middle. He needs a photo opportunity.

every post he attempts is another case of him clacking away alone in the dark, and failing every time all by himself once again.

Re: How to UPGRADE old heating system with modern technology

De acuerdo!

Bravos por Nashua y Pelton!

It's obvious just reading heheheca's posts he doesn't even realize how obnoxious he is to others.

He's living in his own dense self-centered world---the boy in the lead bubble.

Bring Something to the Table

Just love how people post digs with nothing to support them and no advice to bring to the table. I often wonder why I don't see your God, Nashua up with the big boys casting advice in the major leagues.

Guess when you step down to the minors to visit and offer sound advice the bleacher section has to be heard..


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