CH advice please.

[Bob Martin]

I would really appreciate some advice from the CH experts here.

My heating system dates to 1936, with 2-inch pipes and eight flush
radiators. Boiler is 54/74 Thorn floor standing boiler which was
installed in 1982 when I converted from oil to gas.
Boiler is in its own external lean-to building.
It generally works well and keeps our detached 3-bedroom house
comfortable. Apart from a few services it has needed little attention.

Only problem with the pipes is keeping a decent circulation,
needing flushing every autumn, and with my advancing years (81)
getting up & down to the attic is getting difficult.

I got a local firm in to replace the boiler but the guy said modern
boilers wouldn't work with our pipes and rads so recommended
a power flush and a service, which I agreed to.
Heard no more until I contacted them, only to be told that the
"power flush man" would not do it. No reason why.
Google suggests that power flush is not very effective on
large diameter pipes. "Powder flush" is about £1000.

What is my best way forward, please?

[Theo]

Bob Martin <bob.m...@excite.com> wrote:
> I got a local firm in to replace the boiler but the guy said modern
> boilers wouldn't work with our pipes and rads so recommended
> a power flush and a service, which I agreed to.
> Heard no more until I contacted them, only to be told that the
> "power flush man" would not do it. No reason why.
> Google suggests that power flush is not very effective on

> large diameter pipes. "Powder flush" is about ?1000.

>
> What is my best way forward, please?

If you're getting clogging every year on 50mm pipes, that suggests a
substantial amount of corrosion. Are they cast iron rather than copper? Do
you have inhibitor in there?

Just an off the wall thought, but I wonder if it would be feasible to drain
the pipes and push new plastic pipework through the middle of them? They
did that when replacing our cast iron gas pipes with plastic: they redid the
whole street with essentially no internal changes, just a meter change.

It might need some digging out of bends and T junctions that aren't
accessible, but might be less disruptive than re-plumbing, assuming a boiler
replacement is inevitable at some point.

Theo

[Roger Mills]

When I read your post, the same solution occurred to me before I read
Theo's reply.

2" pipes are unusual in a domestic situation - even 40 years ago - and
would normally be used on single pipe gravity flow systems.

What is the pipe layout of your system, and does it equate to any of the
standard Honeywell 'plans'?

Assuming that it's a pumped system, you really need smaller pipes. With
2" pipes,you're heating up a colossal amount of water before it does
anything useful.

--
Cheers,
Roger

[Bob Martin]

Thanks for the reply, Roger,
The system is 80 years old, the boiler is 40 years old.
There is one pipe which goes up from the boiler to the the loft,
then down via 4 drops to the rads, 2 per drop.
There are cavity walls either side of the central stair well, and the drops
are inside the cavities, two each side.

My real question is : is it true that a modern boiler will not work with
this installation?

[Bob Martin]

On 30 Sep 2022 at 12:52:57, Theo <theom...@chiark.greenend.org.uk> wrote:
> Bob Martin <bob.m...@excite.com> wrote:
>> I got a local firm in to replace the boiler but the guy said modern
>> boilers wouldn't work with our pipes and rads so recommended
>> a power flush and a service, which I agreed to.
>> Heard no more until I contacted them, only to be told that the
>> "power flush man" would not do it. No reason why.
>> Google suggests that power flush is not very effective on
>> large diameter pipes. "Powder flush" is about ?1000.
>>
>> What is my best way forward, please?
>
> If you're getting clogging every year on 50mm pipes, that suggests a
> substantial amount of corrosion. Are they cast iron rather than copper? Do
> you have inhibitor in there?

Yes, the pipes are iron.

> Just an off the wall thought, but I wonder if it would be feasible to drain
> the pipes and push new plastic pipework through the middle of them? They
> did that when replacing our cast iron gas pipes with plastic: they redid the
> whole street with essentially no internal changes, just a meter change.

The drops (see my reply to Roger) are inside cavity walls, so not accessible.

>
> It might need some digging out of bends and T junctions that aren't
> accessible, but might be less disruptive than re-plumbing, assuming a boiler
> replacement is inevitable at some point.

I really want to replace the boiler without disrupting the pipework

[John Rumm]

Assuming the basic layout is the same with feed and return pipes and the
rads arranged in parallel between them, I can't immediately see any
reason why a modern boiler could not work with the system - unless there
is a material incompatibility with that much ferrous metal in the
system. Even that seems unlikely given most modern rads are steel
anyway. You would need a decent filter on the return though to protect
the narrow water pathways in a modern HX.

TBH, even if there was a reason to not do it, you could sidestep the
issue with the addition of a thermal store - modern boiler heating that
indirectly, and it heating the rads with its own pump.

I expect this is more a case of it being unfamiliar for the fitter and
perhaps a bit of hassle transitioning to the existing pipes from modern
sizes of copper.


--
Cheers,

John.

/=================================================================\
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\=================================================================/

[Roger Mills]

On 30/09/2022 20:04, Bob Martin wrote:

Very likely. It sounds as if your radiators are in series whereas
systems installed in the last half century have invariably had them
connected in parallel, with one end of each rad connected to the flow
pipe and the other end to the return pipe.

How does the spent water get back to the boiler - there must be a return
somewhere, from the end of the run?

How about getting rid of the big pipe in the loft, and installing 2 new
pipes - a flow and a return. Then connect the two drop pipes to each
rad, one to the flow and the other to the return. You could use 15 or
22mm plastic pipes for the drop pipes, fed down inside the existing iron
pipes in the cavity walls. Not a trivial job, but it should be doable.

--
Cheers,
Roger

[Andrew]

On 30/09/2022 20:08, Bob Martin wrote:

> Yes, the pipes are iron.

Eventually all the dissolved oxygen will dissapate so the
inside of the pipes will not create any more black gunge,
but if you drain the water out and refill with fresh water
then you start the sequence again, unless a LOT of
Fernox is added.

How may KwHs of gas to you use every year, out of interest ?

[Bob Martin]

About 800-900 gas units, times 40?

[Bob Martin]

There are 4 drops (in parallel) each with 2 rads in series.

>
> How does the spent water get back to the boiler - there must be a return
> somewhere, from the end of the run?

The 4 drops combine under the floor, returning to the boiler as a single
pipe.

>
> How about getting rid of the big pipe in the loft, and installing 2 new
> pipes - a flow and a return. Then connect the two drop pipes to each
> rad, one to the flow and the other to the return. You could use 15 or
> 22mm plastic pipes for the drop pipes, fed down inside the existing iron
> pipes in the cavity walls. Not a trivial job, but it should be doable.

None of the pipework after the loft is accessible without tearing the
house apart :-)

[Bob Martin]

On 30 Sep 2022 at 19:08:13, Bob Martin <bob.m...@excite.com> wrote:

Thanks for all the replies so far.

I could get a few more years out of the boiler if the pipes were a bit
cleaner. Is there any good reason why a power flush shouldn't be used?

[Tim+]

Cubic metres? 900 = 10,226 kWhr

Tim

--
Please don't feed the trolls

[Tim+]

I would imagine that it involves pumping stuff around the system. With
wide-bore pipes the flow velocity might be too slow to dislodge or carry
sediment around the system as the pump will be designed for 15/22mm piped
systems.

[Brian Gaff]

But the radiators would be the issue here I think.
It might be time to bite the bullet and get a more modern system. I seem
to recall those older systems did use cast iron pipes, like slightly smaller
versions of what we used to see in schools and the like. If it is, maybe
they would have a significant scrap value?
Brian

--

--:
This newsgroup posting comes to you directly from...
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Note this Signature is meaningless.!
"Theo" <theom...@chiark.greenend.org.uk> wrote in message
news:j8b*QM...@news.chiark.greenend.org.uk...

[Robin]

but with an Imperial meter it's x30-ish so c.25,000 kWh


--
Robin
reply-to address is (intended to be) valid

[Theo]

Bob Martin <bob.m...@excite.com> wrote:
> None of the pipework after the loft is accessible without tearing the
> house apart :-)

Is the top of the cavity wall accessible from the loft? Is the cavity
filled? (you said hallway walls, so I suppose not if it's internal?)

It might be possible to fish new pipes through the cavity with relatively
small holes, roughly the size of an electrical socket. Somebody would drill
a hole at the bottom of the drop, and the drop a new pipe down from the loft
and pull it through the hole. The hole would then be filled - either with
the piece removed, suitably modified, or with a new plug. There would be
some making good of the surface finish, but not massive disturbance. You
could also use plates like these:
https://www.amazon.co.uk/SPEEDFIT-radiator-outlet-plate/dp/B00Q1UXQGI
instead of making good the surface. That plate could live behind the
radiator, out of sight, with just the plastic 'tails' coming out to the ends
of the rad.

If you were to do this I'd install feed and return pipes for each rad, so
you're on a modern system. Then all the plumbing junctions are accessible
in the loft. Ideally I'd do it in 15mm as that allows a more efficient low
temperature system than 10mm microbore, if the radiators were going to be
replaced at any point.

Theo

[Theo]

It would be worth asking the powderflush people what they reckon about 50mm
pipes. It may be, for example, that the surface behaviour of the abrasive
they use isn't as effective - eg because the granules are too small to
effectively scour a wide pipe, as the path of least resistance in the middle
of the pipe is wider.

I'd imagine you could do a liquid power flush with a big enough pump, but it
might not be a piece of kit heating engineers typically have.

On that note, OP, is there a separate pump in your system, or are you
relying on a pump in the boiler? If the latter, you'd need to install a
separate pump suitable for 50mm, which is a bit out of the traditional
comfort zone, but I assume they aren't uncommon on industrial systems.

Theo

[John Rumm]

1 unit is typically 100 cubic feet. So the conversion would be to
multiply by 32.15, giving 25,720 - 28,935 kWh

http://wiki.diyfaq.org.uk/index.php/Gas_units

[Tim+]

With 2” pipes I was assuming no pump at all…

[John Rumm]

On 01/10/2022 08:00, Tim+ wrote:

You can help things by thumping all the pipes and rads with a rubber
hammer (or you can get pads to go on the end of an SDS for the purpose).
The vibration will shift more crud.

Reversing the direction for a second go also helps.

http://wiki.diyfaq.org.uk/index.php/Central_heating_flushing

[Theo]

Tim+ <tim.d...@gmail.com> wrote:
> With 2” pipes I was assuming no pump at all…

Just convection? I suppose that would work, since the return is in the
floor rather thank going back up a drop.

Not sure how that would work with a modern boiler though, especially a
condensing boiler that wants to run at lower flow temps.

Theo

[Bob Martin]

There is a standard pump between the copper pipe from the boiler and
the iron pipe going up to the loft.
(Copper pipe is 1-inch external diameter and iron pipe is 45mm external
diameter).

[Bob Martin]

Yes, there is a standard pump, since I installed a new oil boiler on
moving in to the house in 1969.
Boiler was 90,000 BTU

[Bob Martin]

On 1 Oct 2022 at 13:25:11, John Rumm <see.my.s...@nowhere.null> wrote:
> On 01/10/2022 08:00, Tim+ wrote:
>> Bob Martin <bob.m...@excite.com> wrote:
>>> On 30 Sep 2022 at 19:08:13, Bob Martin <bob.m...@excite.com> wrote:
>>>
>>> Thanks for all the replies so far.
>>>
>>> I could get a few more years out of the boiler if the pipes were a bit
>>> cleaner. Is there any good reason why a power flush shouldn't be used?
>>>
>>>
>>
>> I would imagine that it involves pumping stuff around the system. With
>> wide-bore pipes the flow velocity might be too slow to dislodge or carry
>> sediment around the system as the pump will be designed for 15/22mm piped
>> systems.
>
> You can help things by thumping all the pipes and rads with a rubber
> hammer (or you can get pads to go on the end of an SDS for the purpose).
> The vibration will shift more crud.
>
> Reversing the direction for a second go also helps.
>
> http://wiki.diyfaq.org.uk/index.php/Central_heating_flushing
>

Good idea, I'll do that :-)

[Bob Martin]

On 1 Oct 2022 at 13:21:34, John Rumm <see.my.s...@nowhere.null> wrote:
> On 01/10/2022 06:36, Bob Martin wrote:
>> On 30 Sep 2022 at 20:56:25, Andrew <Andrew9...@mybtinternet.com> wrote:
>>> On 30/09/2022 20:08, Bob Martin wrote:
>>>
>>>> Yes, the pipes are iron.
>>>
>>> Eventually all the dissolved oxygen will dissapate so the
>>> inside of the pipes will not create any more black gunge,
>>> but if you drain the water out and refill with fresh water
>>> then you start the sequence again, unless a LOT of
>>> Fernox is added.
>>>
>>> How may KwHs of gas to you use every year, out of interest ?
>>
>> About 800-900 gas units, times 40?
>
> 1 unit is typically 100 cubic feet. So the conversion would be to
> multiply by 32.15, giving 25,720 - 28,935 kWh
>
> http://wiki.diyfaq.org.uk/index.php/Gas_units
>

Checking my recent gas bills the conversion is 31.4 and my annual
gas use is about 24,000 kWh

[John Rumm]

The conversion between cubic and calorific measures are variable for
natural gas. Normally a bill will show what energy value they used.

(Like it say in the wiki page: "The energy density of natural gas is
typically in the range of 37.5 to 43 MJ/m³")