New boiler

[Eric The Viking]

Many thank to all contributors above.

Our present system is 26 years old, it works for us, we have to turn the heating down many evenings in the winter because we get too warm.

Good points: The rads will be heavy steel sheet & thus probably good for another 30 years. They're not hugely efficient, in that they don't transfer a lot of heat (they don't wast energy either!), but they are solid. The pipe will be thicker too.


Bad points: Might be imperial sized pipe (the fittings are still imperial threads even today, around much of the world!). I _would_ worry about de-zincification, especially anywhere subject to cold and damp in the summer (spare room, etc.). Take great care undoing fittings, as apparently solid rad valves (especially, as they're next to steel) can just squish when a Stillson wrench is applied.

Checking for corrosion:

If you've had corrosion proofer in the system (Fernox, back then), it's probably fine. When the system is on, feel the bottom centre of big rads. If it's stone cold after a few minutes running (the top should be very hot), the bottom tube is full of sludge, blocking the flow.

Whilst this is corrosion, it's probably not terminal. With care you can restore any lost efficiency by removing the radiators and flushing them over a drain in the garden. I use a jet-wash with a drain cleaning attachment. On single rads, the 'bullet' will pass through the top and bottom tubes, scouring rust and crud away as it goes. It can be harder with double ones, depending on the design, but still do-able. The physical shape of modern rads makes this almost impossible.

A good corrosion test in two parts:

(1) Draw off a jam-jar full of circulating water from the drain **** (usually near the boiler, but close to the lowest point on the system).
Check for black (bad) or brown sludge (worse). There will always be some, but it should settle out fairly quickly. If it's like soup the system needs flushing completely before doing anything major to it, and that process may (will) reveal leaks.

(2) Put a big, degreased wire nail in said jam-jar of soup, leave it standing on a sunny windowsill for a week or two with the top open (corrosion needs oxygen to go 'well') and observe: if the nail rusts your corrosion proofer is absent or too diluted, and the system almost certainly corroded internally. If it doesn't, it's probably fine (but see brass fittings)

However, the three way motor valve broke down last spring and I haven't repaired it yet, radiators are looking tatty, wondering whether to soldier on or look at the costs before Ossy gets his pen out.

They do it all the time. The mechanics of 2-way and 3-way valves are truly dreadful - a stepper motor+gearbox stalled against a spring with limit microswitches to tell the controller where it's 'pointing'. Replacements are pretty cheap, around £12-15, and for big-name valves (Honeywell, Danfoss, etc.) you can get the motor head separately. You might be able to swap the motor head without replacing the valve body. If it's not leaking, that's a cheap fix.

so a condensing boiler is what? our present boiler has the flue outlet on an outside wall, also the air inlet in the same grill. It is also fitted into our kitchen units at floor level and I don't want a new kitchen as well. Will a condensing boiler just pop into the existing boiler cupboard do you think?

It will physically fit - new boilers are more compact - but the flue may not line up, and you may need to make a smaller hole above the 'balanced flue' you presently have. Modern flues are not only small, but the exhaust from a condensing boiler is CO2 and water at low temperatures, so they don't really need any safety grille round them. You can easily make the necessary hole with a diamond core drill, and brick up the old square one.

"Condensing" means having two or three heat-exchangers in series, so that the last tiny bit of heat from the gas is used to heat the water. The condensing part is removing the latent heat of the steam produced, by condensing it to water ("cloud") inside the boiler before it leaves the flue. It's why you see a plume coming from the things in cold weather - it's the condensed steam as a cloud. A by-product of the process is an acidic soup caused by (I think) the formation of carbonic acid and residual amounts of sulphur compounds (from the fuel gas), which is what has to be separately drained away from the 'condensate trap.'

A final thought: the new boiler technologies are characterised by two things: lots of narrow pipework, & complex control systems. If fitting a new boiler to an old system, your plumber should thoroughly flush the system before and after installation. The first gets rid of old sludge, and the second gets rid of copper filings, soldering fluxes, etc.

Old boilers didn't care much about sludge - it made the pumps fail occasionally, but otherwise didn't do a lot of harm. On new boilers, sludge can cause expensive early failures. We fitted one of these, and it's brilliant (not cheap, but less than two hours of my plumber's time). They only really work _after_ the system has been cleaned, but work they most certainly do!

HTH,

E.

 

[devonwoody]

Many thanks above for time and advice.
I understand much more about this subject with the information given.

I will get some quotes in and also have much more knowledge in what is being discussed.

 

[RogerS]

dw...forgot to say that over on AskTheTrades there seem to be more problems with Baxi then any other make.

 

[Digit]

Reading your posts DW it sounds as though you have no room stat for temp control, is that correct?

Roy.

 

[devonwoody]

Reading your posts DW it sounds as though you have no room stat for temp control, is that correct?

Roy.

Correct digit, I think the information at the time of installation was that the boiler setting would be the best way of controlling output.
We are detached with four very exposed external outlooks and one temperature stat might not suit other rooms.
Rad.stats were not economical to fit at the time 26 years ago either.

 

[Lons]

Reading your posts DW it sounds as though you have no room stat for temp control, is that correct?

Roy.

Correct digit, I think the information at the time of installation was that the boiler setting would be the best way of controlling output.
We are detached with four very exposed external outlooks and one temperature stat might not suit other rooms.
Rad.stats were not economical to fit at the time 26 years ago either.

DW

If you end up with a whole new system (you'll need deep pockets), they will put in a room stat. / hw cylinder stat (if you retain the cylinder), and trvs to all rads, except possibly one as a bypass. (don't know if that's still good practice). :?

Assuming you've taken advantage of cheap loft and wall insulation deals, you will save a surprising amout of money on heating.

Or....discard all those layers of sweaters :lol: :lol:

cheers

Bob

 

[Digit]

Wot 'e said DW, in fact I doubt that you could run a condensing boiler without a room stat. Modern stats are available with battery power and a radio link to the boiler so no damage to your decorations need occur.

Roy.

 

[Eric The Viking]

Wot 'e said DW, in fact I doubt that you could run a condensing boiler without a room stat.

I do. If you have rad stats, I can't see what purpose they serve.

 

[wobblycogs]

AIUI if you have passive rad stats - e.g. they control flow to the radiator rather than the boiler itself - then a main room sensor is necessary to control the firing of the boiler. My guess is that as you don't have a room stat your boiler is stopping firing because the flow or return water temperature is at the maximum allowed value. I believe building regs now require both a room stat and radiator valves minimum for a new installation.

 

[Dibs-h]

Wot 'e said DW, in fact I doubt that you could run a condensing boiler without a room stat.

I do. If you have rad stats, I can't see what purpose they serve.

We don't have one either and have no issues with the system.

 

[Digit]

I'll re-phrase my comment, it's not a good idea to run without a room stat.
When the last TRC shuts down the boiler will recirc the water through its own, or an external by-pass loop, if fitted, till its own internal stat shuts it down.

Roy.

 

[Digit]

Do you have a condensing boiler Dibs?

Roy.

 

[Dibs-h]

Do you have a condensing boiler Dibs?

Roy.

Yep. All the rads are on TRV's except one in the bathroom which isn't and is set about 1/2 all the time.

Will be seeing my CH chum tonight so will be bringing it up.

 

[sparkymarky]

room stats should be fitted in a room with no TRV. this in theory would make the stat shut down the CH system and keeping the house at the design temperature, thus preventing any other rooms being cold, however in my experience this doesn`t work, the stat shuts down and you`re left in a cold room.
easy way to solve this is to get a good wireless room thermostat (i`ve fitted quite a few of this one http://www.plumbnation.co.uk/site/honey ... -hc60-set/) then not fix it to any walls but just carry it into the rooms that you are in throughout the day.
this will then provide full boiler interlock shutting the system ch pump down saving you electric and also stop the heat being needlessly wasted by being circulated, it would also stop the boiler short cycling (firing on and off lots) witch can shorten the life of you`re boiler.

 

[wobblycogs]

The heating system we're installing is built around these things http://www.screwfix.com/prods/79143...Guest-JGSTAT-Programmable-Room-Thermostat-12V. Each room, or smallish group of rooms, has one of these fitted and it's wired back to a fancy control box using (basically) Cat5e network cable. It's quite an expensive system to fit but in a large or poorly insulated house* it save money by allowing you to heat only those rooms that you are occupying. The single room heating is achieved by having each room stat control a separate actuator on a manifold like this: http://www.screwfix.com/prods/77395...nderfloor-Heating/JG-Speedfit-6-Port-Manifold. So far we have done all the plumbing an wiring ourselves with the exception of fitting the boiler and sealed hot water tank - never again .

* like ours which has solid brick walls and single glazing - and because it's listed we can't do anything about the windows, sigh.

 

[Digit]

One other point DW, if you are much into showering I would give combis a miss, same again if you're in a hard water area.

Roy.

 

[Eric The Viking]

One other point DW, if you are much into showering I would give combis a miss, same again if you're in a hard water area.

Roy.

They're certainly slow filling baths. They should also have descalers fitted on the cold feed (for the domestic hot water), unless you're in a very soft water area. Fernox do one intended for the porpoise, which uses consumable softener crystals. If you don't do this, they tend to lunch the hot water diverter valve in short order, which is *really* expensive to repair.

Aside: the lack of hot water flow is why we have a pressurised DHW tank. Because it's bang next to the boiler it works bit like a combi, but with a far better flow rate.

Incidentally, I can't see the point of individual room thermostats and separate solenoid valves. It all sounds far too complex when you'd get the same result from stats on the relevant rads. They're pretty reliable really, and need no power nor wiring. I suppose you can put the whole lot on timers and/or run it from a simple command centre:

D'oh! Why didn't I spot that (homer)

 

[wobblycogs]

Separate room stats are great if, like me, you work from home. I can turn on the heating for just my office and leave the rest of the house just ticking over which saves a ton of power compared to a more standard set up. Yes, I suppose you could get the same effect with passive radiator stats but it would mean going round to every room turning them up and down twice a day.

The room stat I linked too learns the heating curve of the room too. If, for example, you set it to make your bedroom 18degC at 9:30pm over the course of a few days it'll learn that it needs to start heating the room at about 8:30 say if the temperature is currently 15degC.

It's certainly not a system for everyone at the moment as it's still too expensive but I would be surprised if we didn't see houses being built with this type of system in a few years.

 

[Lons]

The room stat I linked too learns the heating curve of the room too. If, for example, you set it to make your bedroom 18degC at 9:30pm over the course of a few days it'll learn that it needs to start heating the room at about 8:30 say if the temperature is currently 15degC.

Gotta get me one of those 8)

Does it overide the missus p****** about with the thermostat every ten minutes and mucking up the status quo?

Bob

 

[wobblycogs]

You can install a separate master control box that can be used to lock all the other thermostats and can be password protected. If you are feeling really rich you can even get a box that lets you control your heating over the web or even by SMS. The latter two options are more designed for small hotels (or the mega-rich) though.

We saw the system at the house and home building show at the NEC, as we had to completely wire and plumb the house it made sense to fit it. You can normally pick up free tickets for the show, it's worth heading along if you like your building and gadgets.