Insulating Boiler CH Megaflo pipework

[craigski]

I have a condensing boiler providing DHW via megaflow and CH. Installed about 10 years ago in the attached north facing (cool) garage, with no heating (apart form 'leaking' heat from pipework).

It seems my DHW system is using more energy than it should:

http://www.navitron.org.uk/forum/index.php/topic,14508.0.html

There is lots of pipework, valves etc, but none of it is insulated. Much of the pipework is surface mounted, but only 10mm space between pipe and wall due to the pipe clips used.

Im assuming I should insulate as much of the pipework as possible? Does this include the flow / return pipework from boiler? Should I insulate right up to the compression joints on the flow return pipework from boiler?

Can anyone who has done this recommend any products I should use, based on the limited space I have behind the pipe work (10mm)?

[SimonHobson]

Is the wall internal or external ?

If it's internal (and so any heat lost through it isn't really wasted) then a compromise would be to insulate over the pipes but not behind. 10mm isn't much of a gap, so you aren't going to get much in anyway.
One method is to box round and fill the space with glassfibre or similar. The pictures in this thread might give you some ideas.

But in answer to the other part - you should insulate as much as is possible. If you work out the area of a length of copper pipe then it soon adds up - and all that acts as a radiator to lose heat.

[craigski]

Thanks for the link to pictures Simon, if only the pipework I have 'inherited' was as well laid out as yours

My boiler is mounted on external wall, this is where the 28mm copper pipes are 10mm or so from wall. The way the pipes are laid out is not ideal, eg there are pipes running 90deg to other pipes, and almost touching, some of the pipework is only 10mm from external wall.

I have measured the total length of the 'hot' (ie flow/return for CH & HW, and also hot water feed from megaflow) uninsulated copper pipes:

28mm is 5.9m
22mm is 6.6m

I found heat loss here:

http://www.engineeringtoolbox.com/copper-pipe-heat-loss-d_19.html

So I estimate over 800w loss when the garage is at 10deg or so in middle of winter, and that excludes pump & valves etc 

My plan is to use climaflex, using the thick possible. I will only be able to use 13mm where there is only a 10mm gap, but can use thicker (25mm) where possible.

Is there any value in wrapping the climaflex with foil tape?

Or use something like:

http://www.screwfix.com/p/spiral-wrap-50mm-x-7-5m/62194

[JohnS]

I had a similar problem once but it was only a short run of 50cms.  I used the thicker insulation and sliced a segment off it.  I ended up with something like a D shape that fitted over the pipe with the flat part of the D up against the wall.  You have to slice where the slit is, so you cannot tape up the slit.

Might be a bit tedious for 12.5m.

John 

[craigski]

Its only some of the pipe work that is 10mm from external wall, not the whole 12.5m, the picture below shows most of the pipework. The pipes to the right of the boiler are on external wall, the pipes to rear (where the electrics are) on on internal wall next to kitchen, again only 10-15mm from wall, but pipes are very close together, so still limited space between pipes to use thickest climaflex.





I like your idea of making the climaflex 'D' shape

[SimonHobson]

As plumbing goes that's actually quite neat and tidy - but then they revert to true "plumber of the worst kind" by completely ignoring insulation. Even 10 years ago it was recognised that pipes need insulating I've done what JohnS suggests as well, it tends to work quite well and I think in this situation is about the best you'll manage. With some care you might possibly be able to glue the slit together round the back of the pipes, but it could get messy

[acresswell]

I ended up with something like a D shape that fitted over the pipe with the flat part of the D up against the wall.  You have to slice where the slit is, so you cannot tape up the slit.

Might be a bit tedious for 12.5m.

I did something pretty similar on my last project.  I found that if I eased the pipe out from the clips, I could get the insulation round it without needing to "slice where the slit is", and I could then just ease the pipe back into the clips afterwards.

I used a small mitre box to speed up the cutting... I lay the insulation down in the mitre box, packed it underneath with some odd bits of hardboard to lift it up slightly, then ran a bread knife along the top surface of the mitre box, skimming the top off the insulation. With the mitre box clamped in a vice it became quite quick to hold/move the insulation with one hand whilst cutting with the other.

I can also recommend the D-shape insulation for use under floorboards if you inherit a system where the pipes have been run in notches in joists... normally there isn't enough gap between the top of the pipe and the underside of the floorbaord to fit in any unmodified insulation.

HTH,

Adrian

[craigski]

Thank you all for your comments, much appreciated.

With some care you might possibly be able to glue the slit together round the back of the pipes, but it could get messy

I was going to use foil tape to wrap around the climaflex? I was thinking where it is tight against the wall (ie between the wall and the flat edge of the 'D') I could use the non-stick paper (the stuff you peel off the back of sticky labels etc) with the tape stuck to this, push through and then remove the non-stick paper, and wrap the tape tightly around the pipes?



A couple of questions before I embark on this project:

1) How close should I insulate up to the boiler? The flow/return come out vertically from top of boiler (see photo above), should I leave the vertical run uninsulated and start after it turns 90deg? ie leave about 6" ?

2) What tape should I use to seal the joins? ? Foil tape ? Duck tape?

eg http://direct.tesco.com/product/images/?R=202-0824

or http://www.screwfix.com/p/no-nonsense-aluminium-foil-tape-silver-72mm-x-45m/50629

Adrian - thanks for the bread knife tip. I will prob make a small jig using small MDF offcuts I have the garage. I knew the offcuts would come in useful one day

[SimonHobson]

Insulate as much as is practical - right up to the boiler casing if you can, but leave enough of a gap to allow the cover to be removed for servicing. A larger size of lagging is useful for going round fittings (compression joints, valves, etc).

I bet your other half keeps moaning about the "rubbish" you keep (does she ask why you want to keep those bits of old wood ?) - my mother is always on about the rubbish (her term - we call it "materials") dad and I keep collecting

As for tape, I think I've tried that trick in the past and I don't recall much success. I've probably been using the wrong sort of tape, but I've always found it eventually dries out and peels off. I recall when they were putting a chilled water system at my last job, they used some rather horrible and sticky glue to seal the insulation. Where bits were done later by the "handyman" with duct tape - it was all hanging off within a year or two. The little bit I did (in the server room) I used carpet glue I blagged from the carpet fitters one time - it's still there after a good ten years.

[acresswell]

I used duct tape, which seemed pretty successful.  Long straight lengths along each slit worked OK, except they had a slight tendency to peel off from the ends, until I added a separate bit wrapped round the cuircumference at each joint.

...and SWMBO has just pointed out that it's also easy to label the pipes if you write on the tape with a thick marker pen!

[SimonHobson]

I used duct tape, which seemed pretty successful.  Long straight lengths along each slit worked OK, except they had a slight tendency to peel off from the ends, until I added a separate bit wrapped round the cuircumference at each joint.

I've always found that method "quite tricky" as you seem to need about 5 hands minimum - at least two to hold a strip of tape so it doesn't fold itself up into a sticky tangled mess, and several hands to hold the insulation in place and the slit closed - I've seen several jobs where the tape has be stuck so as to hold the slit partially open. Also, it depends on the tape, but a lot of "duct tape" tends to dry out and peel off in time.

...and SWMBO has just pointed out that it's also easy to label the pipes if you write on the tape with a thick marker pen!

And of course, you can normally write directly on the insulation itself.
If you really want to look swish, go out and buy some proper identification tapes.
http://uk.rs-online.com/web/p/safety-posters-labels-tapes/0711485/
http://uk.rs-online.com/web/p/safety-posters-labels-tapes/0711378/

Or these days, you could just print some stickies given the capabilities of most modern printers.

At my previous employer, we had a chilled water system installed for air con in the offices. Quite a sizeable installation and not a single pipe labelled. One day I just got really p***ed off at having to do the mental gymnastics to work out which was which after going half way round the building* that I bought some tapes and went round labelling them all.

* Have you ever heard the hammer you can get from one of those thermo-hydraulically actuated valves when you connect it the wrong way round on a system with long pipe runs
Mind you, the guys that connected up the first few units as they installed the system managed to get the connections wrong on the 3 port diverter valves - I think they managed ever possible combination of wrong, even after having it explained several times

[KLD]

Craigski

In your other thread you found that minimizing the boiler ON time didn't do that much about the energy input. Your 11 kWh per day for two short showers are still fantastically high. I would guess that the main culprit is standing losses from the cylinder. You probably said it somewhere already, but what is the temperature you heat the cylinder up to? Can that be lowered?
The hot outlet from the cylinder rises straight up, in 22 or even 28mm pipe, inviting in-pipe convection. Doesn't this pipe feel hot when you touch it? Likewise the feed pipes to the boiler coil, they go either horizontally or up from the cylinder. These would be the first pipes I'd concentrate on insulating.
How thick is the insulation of the cylinder itself? How old? Any chance on boxing the whole lot in? Could the three-port valve be moved away a little to make room for a box? Would you have enough room left for servicing the boiler?

Ideally you take a few temperature readings of the tank before you start, so that you have a baseline against which you can judge the success of your efforts. Sure, the gas consumption is a good indicator, too, but a more direct measure would certainly help you along.

Klaus

[craigski]

Klaus, the ON time (now 30 mins in morning and 30 mins in evening) reduced energy input from 13kWh to 11kWh.

Cylinder is set to 60degC.

Outlet is 22mm, and I measured this to be 25degC at the outlet of the megflow, this was measured with a fluke IR thermometer, so approx temp.

The Megaflo cylinder is about 10 years old, it just has the standard builtin insulation 35mm of injected foam around the cylinder, then the plastic case around that.

I found a spec here that says Energy loss of my Megaflo CL170 is 2.28kWh per day, (the newer 'eco' 170 model is rated at 1.42kWh per day).

Boiler manual says 86% maximum efficiency, lets assume 80%?

11kWh x 80% = 8.8kWh

8.8kWh - 2.28kWh = 6.5kWh

I dont know what the loss of the unlagged pipework would be, but it looks like Im only getting 50% of the input energy back as hot water 

I have purchased the climaflex, and will start lagging this weekend I hope. Will report back if it has made any difference.