Central heating question

  • Thread starter Darby O'Gill
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Darby O'Gill

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Hello all.

I’m looking for advice or suggestions on installing a secondary heating option in my house.

My existing set-up is as follows-

I have an oil-fired system serving the entire house, installed in 1999. The boiler is a Firebird popular 120, producing a nominal 120,000 BTUs. The system is divided into three zones- downstairs, upstairs and hot water. In terms of usage, we use downstairs a lot this time of the year, upstairs less so. As we have electric showers, we only use the hot water for washing-up needs, and the occasional bath.

I’m considering replacing an open fire with a multi-fuel stove. What I want to do is use a back boiler on the stove to heat the downstairs rads. There would be no particular difficulty running pipe work to the hot press where all the various connections are located. The distance is not great and while I would have to go through a couple of internal walls, I would not have to open floors, as the pipes would be mostly hidden under the stairs. My questions are-

  • What is involved in tying in a solid fuel system to the existing system? Will I need additional items apart from stove, boiler and associated pipework?
  • In practical terms, how would the two systems operate together? For example, could I run the oil for an hour or so until the stove was fully fired up?
  • Is this a difficult plumbing job or relatively straightforward?
  • Any other issues to consider?

Thanks.
 
It is possible depending on your current system and how it is set up and wired. If your existing system is sealed I.E no small tank in attic, you will need to change it to open vented. you will need to get a dual coil cylinder, when stove is piped into radiator system it will need to bypass motorised valve, I.E downstairs zone is always open to stove line when it is hot. A good plumber will be albe to talk you through it. Make sure the right person does it as it may get a bit tricky and they will need to have done this kind of thing before.
 
Thanks Davy. I hope to get the plumber who installed the system to do the job- just wanted to get a bit of background first to assess the complexity etc. As you've figured, I have motorised valves, controlled by timer/thermostats as required.

What does open-vented mean? Does this refer to the need for a tank in the attic? (I only have my cold water tank up in the attic, so I'm pretty sure I have a sealed system).

What is a dual-coil cylinder for?
 
you have a sealed system with an expansion vessel(usually round and red). when the system heats the water expands into this vessel. If the system ever got too hot the boiler has safety stats that will automatically shut it down. Safety valves are also fitted to system preset to open if pressure exceeds 3 bar.

open vented = no vessel but little tank high up in attic. it has a pipe from the heating system that bends over little tank called expansion pipe. When system heats, water rises up expansion pipe.
Because a stove has no safety thermostats I.E you can not control temperture of natural fire you would need to allow the expanding water go somewhere I.E up expansion pipe and if needs be pour into expansion (little tank) this would only happen if the pump on the stove line went down due to failure or power cut.

Oil boiler + power cut = boiler shut down
stove + power cut = Very hot, still lit stove with boiling water in pipe work that needs to be able to safety expand some where.

If pump is running there is no problem. A good installer always thinks worst case and prevents.

Dual coiled cylinder is a cylinder with two coils. you will need to prevent the stove sending hot water to oil boiler (treating it like a huge radiator, very costly and pointless) and like wise when oil boiler is on sending hot heating water to stove. this is best acheived by using a dualed coiled cylinder and non return valves.
 
Thanks Davy- fantastic explanation. If you're not Ireland's richest plumber, there is no God.....
 
one other thing...

For best results, this is how we do it. Run two 1 inch pipes to cylinder coil 1. flow and return. pipe, so natural circulation takes place I.E hot water rises to cylinder and cool water falls to stove naturally (no pump) there is a thermostat on flow at cylinder and when it reaches a preset tempature it sends power to pump that is tee'd off the cylinder line and connected to radiator system. pump comes on and sends heat to rads. thermostat cools down and shuts off pump. this cycle continues. No power to pump and cylinder absorbs heat from stove.

oil boiler goes to coil 2 and is tee'd into rad system. where these tee's are is where the non return valves are fitted on both branchs off lines 1 and 2. so when oil boiler pumps comes on it can't send hot water into stove cyliner line and like wise when stove pump comes on it can't send hot water into line of oil boiler to cylinder.

Your plumber will be able to explain it better standing infront of you.
 
Thanks again Davy.

Our existing cylinder is on the ground floor, so that presumably means I'd have to fit a new pump to send the stove water around- I'm guessing the cylinder will not gravity-feed the system as you suggest??
 
Well, thought I'd give an update as I see there are a lot of stove-related questions these days.

Bad news: We have dropped the idea of a back-boiler stove. The layout of the house just makes it too much hardship. It would involve ripping up most of a bedroom floor upstairs, and ripping up part of a wooden floor downstairs before cutting a channel for a pipe. Not to mention changing the cylinder, effectively rebuilding the hot press and making holes in the chimney in a few places, going through a couple of walls etc. My plumber would give me a quote if I wanted, but he just thought it would be too expensive and not worth the stress- we accepted his advice.

Good news: We are installing a stove. The plumber suggested we go ahead with a non-boiler model as the open-plan layout of our living area makes it ideal. He has suggested we consider replacing our ten-year old oil boiler with a condensing model, as well as fitting three thermostatic radiator valves in the living area. This means those rads would cut out once the stove got the room up to our preferred temperature, making an extra oil saving. I'm awaiting a quote for this.

Better news: Got a year-old Stanley Erin stove off my aunt for a pittance. Had to buy a few bits (top marks to Gings in Portlaoise) but the stove is here and in great order.

I'm waiting for my builder to come tomorrow to widen the chimney opening so we can set the stove back a bit- it's only 18" so the stove won't fit. I've already taken out the old fireplace, fireback and hearth and loosely installed the 8" to 6" flue adaptor pending final fitting of the stove. I'll get a plasterer to tidy up the opening once the builder is done, paint it up, fit a new hearth (to be purchased), and fit the stove.

Will post when it's done to let you know how it went. Hope this helps somebody......

Thanks to Davy Jones for his advice.
 
Sorry for hijacking the thread this interests me too. I have a sealed oil fired central heating system. I also have a cooker with a back boiler which heats the water.I would like this cooker to heat the radiators as well. This cooker is beside the hot press where the copper cylinder is.

My questions are:
1. Is it a big/expensive job to change to an open system
2. Are the only pipe runs neccesary between the cooker and hot press or
will it be neccesary to run some back to the oil burner
3. Will I need to change the copper cylinder even though it already heats the water.

Thanks in advance.
 
1 no
2 hopefully you can connect into rad system in hot press
3 no

These are the short answers.
 
Re: Central heating question/stove

Well, here's the update I promised for anyone interested.

The stove is in and working. Here's a breakdown of the work and costs-

1. Blocklayer put in a new 4" concrete head to support the chimney breast. This involved cutting a slot either side of the breast just under the existing flue retainer to allow the head go in under the flue retainer. Once the head was in place, he cut out 9 inches of blockwork either side to make a 36" opening instead of the original 18". €150.
2. Plasterer bonded plasterboard around the opening and put a skim coat on it. Finished ope is 33.5 inches. €120.
3. As we were putting the new hearth flush with the floor, I needed a carpenter to cut back the wooden floor to suit. €20!! for a tough hour's work (solid maple).
4. Fitted the polished slate hearth myself. Put it down on some lean mix sand and cement. Hearth is in two pieces and cost €220. It's very nice.
5. Due to tolerances/access being too tight, we had to forget about going out through the top flue. Fitted a stainless steel 90 degree bend and about a foot of flue to the rear exit instead. Had to spray them black to match. Previously fitted the flue adaptor and sealed it in place in the chimney (€62). Flue €30, paint €12.
6. Used four off-cuts of carpet under the legs to allow me to move the stove about on the slate without gouging it. Once in place and squared up, put in lots of fire cement/sealant in the two joins in the pipes. Messy and awkward due to the low opening.

Today is our second day with it lit. Lots of interesting smells last night, due to paint curing, fire cement hardening, (paint burning?) and assorted dust burning off. Much more pleasant today, although getting the fire just right is taking a bit of practice. Plenty of heat, but turf really blackens the glass.

I'm not sure the plasterboard is the best idea to form the ope with, and I doubt the paint on it will last. If not, I'll re-do it in the spring with something else. There's heat-resistant plaster which I might try.

So that's it. It looks lovely and really heats the rooms. Will source some good wood as soon as possible- coal is king for the moment though...
 
Hi Guys

Just picking up on the questions of your problem with the stove as regards to an open vented system and sealed systems.
This is one for the plumbers out there you can now get a stove that you can connect to a sealed system with no problems it has a stainless steel boiler and numerous other features.
I know this as we had the same problem as you with connecting a stove as we couldnt get natural circulation for a standard stove.
We employed the help of a company that supply a sealed stove and to date we now only use our oil boiler as a back up.
DavyJones might be interesred
 
Hi Folks, Am interested in combining Solid Fuel and Pressurised system. I would be grateful to you Magtape if you could enlighten me as to who this company is that makes this boiler that can be integrated into a pressurised system? Thanks in Advance.
 
magtape said:
...... you can now get a stove that you can connect to a sealed system with no problems ......
Click to expand...

I'm sure somewhere in the small print there is a condition that you must not light the fire in the event of a power failure and there would have to be a heat leak zone for the exclusive use of the stove, also you may be prohibited in your choice of solid fuel - ie no coal.

Can you post a link to product, if available?

Any solid fuel stove (vented) can heat a thermal store from which you obtain the heat for your rads by heat exchanger, hence the impression that you are using a pressurised system.

Good diagram here on thermal store
http://www.boilerstoves.co.uk/boiler-stove-installation-D.html
 
Can't get your link to work, david.

magtape, I am interested.What was the name of the company and the stove?

I know system link do a thermal store and can be used on pressurised system but as far as I know you still need natural circulation to thermal store.
 
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