My house has heating piped to the single pipe system=20
Standard TRVs can't be used on a single pipe system. To turn off a single pipe fed radiator, you need to effectively short circuit it rather than cut off the water. TRVs are not designed to do this.
If the rads are permanently bypassed and just rely on convection from the pipe to circulate, this may be unsatisfactory with TRVs due to the narrow bore and pressure loss. It may work, but I wouldn't count on it.
Also, I'm not sure if the fully pumped primary circuit requirement of Part L will preclude the local convection circuit as well. The requirement for a fully pumped primary circuit is so that the radiators will heat up quickly, heating the house quickly, so that the primary circuit doesn't need to stay hot for long. If the rads themselves are convection circulated, they will take an age to heat up and the boiler may sit there on low power for long periods unnecessarily.
Christian.
Indeed. While it should work just the same as before, which is fine, it wont comply due to the lack of TRVs. And adding those appears non-trivial.
So your choice is a complete replumb, or a non compliant system that works fine but without TRVs.
NT
| Christian McArdle wrote: | > > Apart from fitting thermostatic room valves, and getting rid | > > of a small amount of sludge. | >
| > Standard TRVs can't be used on a single pipe system. To turn off a = single | > pipe fed radiator, you need to effectively short circuit it rather = than cut | > off the water. TRVs are not designed to do this.
Not my experience, the one I had worked fine on a single pipe pumped system. =20
| > If the rads are permanently bypassed and just rely on convection from= the | > pipe to circulate, this may be unsatisfactory with TRVs due to the = narrow | > bore and pressure loss. It may work, but I wouldn't count on it. | >
| > Also, I'm not sure if the fully pumped primary circuit requirement of= Part L | > will preclude the local convection circuit as well. The requirement = for a | > fully pumped primary circuit is so that the radiators will heat up = quickly, | > heating the house quickly, so that the primary circuit doesn't need = to stay | > hot for long. If the rads themselves are convection circulated, they = will | > take an age to heat up and the boiler may sit there on low power for = long | > periods unnecessarily. | >
| > Christian. |=20 | Indeed. While it should work just the same as before, which is fine, it | wont comply due to the lack of TRVs. And adding those appears | non-trivial. |=20 | So your choice is a complete replumb, or a non compliant system that | works fine but without TRVs.
I had one TRV in the old system which worked fine for 25 years, so I will just add TRVs which does not look too difficult.=20
--=20 Dave Fawthrop
17,000 free e-books at Project Gutenberg!
I don't think you'll have any problems adding TRV's to a single pipe system. The heat output from the radiators might be an issue. The condensing boiler will try to set the return to 50C or lower, which means radiators at the colder end of the loop could be very seriously undersized.
| In article , | Dave Fawthrop writes: | > My house has heating piped to the single pipe system=3D20 | >=20 | > My single loop was pumped. All pipeing is metric copper, with steel | > radiators. | >=20 | > This has heated the house satisfactorarily for 25 years. | >=20 | > I am replacing the old boiler with a combi, condensing boiler, and | > intend to use the same pipes and radiators, to the latest Part L = regs, | > which I have downloaded and skimmed. | >=20 | > Apart from fitting thermostatic room valves, and getting rid of a | > small amount of sludge. (the system has always had Ferinox in it) I | > can see no problems. | >=20 | > Can others see any problems with this? |=20 | I don't think you'll have any problems adding TRV's to a single | pipe system. The heat output from the radiators might be an issue. | The condensing boiler will try to set the return to 50C or lower, | which means radiators at the colder end of the loop could be very | seriously undersized.
I have added extra insulation and draught proofing to the house since I did the heating calcs and sized the radiators *long* ago, so I think the radiators though small will be OK.=20
--=20 Dave Fawthrop
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I'm guesing, but it might just work quite well, the radiators at the end of the run would have had to be seriously oversized to deal with the lower temperatures. Though I suppose the overall design might have been 80/70C and not anything lower.
If I were faced with this, I'd square up to having to add the extra pipe but I'd try it with the TRVs and single pipe first and see how well it worked.
| On Thu, 05 Jan 2006 19:45:28 +0000, Andrew Gabriel wrote: |=20 | > In article , | > Dave Fawthrop writes: | >> My house has heating piped to the single pipe system=3D20 | >>=20 | >> My single loop was pumped. All pipeing is metric copper, with steel | >> radiators. | >>=20 | >> This has heated the house satisfactorarily for 25 years. | >>=20 | >> I am replacing the old boiler with a combi, condensing boiler, and | >> intend to use the same pipes and radiators, to the latest Part L = regs, | >> which I have downloaded and skimmed. | >>=20 | >> Apart from fitting thermostatic room valves, and getting rid of a | >> small amount of sludge. (the system has always had Ferinox in it) I | >> can see no problems. | >>=20 | >> Can others see any problems with this? | >=20 | > I don't think you'll have any problems adding TRV's to a single | > pipe system. The heat output from the radiators might be an issue. | > The condensing boiler will try to set the return to 50C or lower, | > which means radiators at the colder end of the loop could be very | > seriously undersized. |=20 | I'm guesing, but it might just work quite well, the radiators at the = end | of the run would have had to be seriously oversized to deal with the = lower | temperatures. Though I suppose the overall design might have been =
80/70C | and not anything lower.=20Actually I have *four* single pipe runs, the maximum number of rads on a pipe is three, two with two rads and one with one rad. The two with two rads are the main downstairs ones, the others upstairs will be in another zone which will be rarely used. =20
It strikes me that the first rad on the pipe will get its room up to temperature the TRV will shut down and the heat will pass on to the next one down the line. Thus there will be only be a short delay in getting the downstream rooms/rads up to temperature.
I have looked at the repiping option and did not like the conclusions I came to.
--=20 Dave Fawthrop
17,000 free e-books at Project Gutenberg!
Why would you tell us you have a certain type of system, ask for advice on it, then tell us in fact its something vey different?
NT
| Dave Fawthrop wrote: | > | > Dave Fawthrop writes: |=20 | > | >> My house has heating piped to the single pipe system=3D20 | > | >>
| > | >> My single loop was pumped. All pipeing is metric copper, with = steel | > | >> radiators. | > | >>
| > | >> This has heated the house satisfactorarily for 25 years. | > | >>
| > | >> I am replacing the old boiler with a combi, condensing boiler, = and | > | >> intend to use the same pipes and radiators, to the latest Part L= regs, | > | >> which I have downloaded and skimmed. | > | >>
| > | >> Apart from fitting thermostatic room valves, and getting rid of = a | > | >> small amount of sludge. (the system has always had Ferinox in = it) I | > | >> can see no problems. | > | >>
| > | >> Can others see any problems with this?
I note that you have snipped crucial bits of the discussion
| > Actually I have *four* single pipe runs, the maximum number of rads = on | > a pipe is three, two with two rads and one with one rad. The two | > with two rads are the main downstairs ones, the others upstairs will | > be in another zone which will be rarely used. | >
| > It strikes me that the first rad on the pipe will get its room up to | > temperature the TRV will shut down and the heat will pass on to the | > next one down the line. Thus there will be only be a short delay in | > getting the downstream rooms/rads up to temperature. | >
| > I have looked at the repiping option and did not like the conclusions | > I came to. |=20 | Why would you tell us you have a certain type of system, ask for advice | on it, then tell us in fact its something vey different?
Everything I wrote in the first post was correct, within the limits of a reasonably short post, and not including things which appear irrelevant at first. It is a universal problem with usenet, that one can not know where discussions will lead. In this case discussing a problem which I had not anticipated.
--=20 Dave Fawthrop
17,000 free e-books at Project Gutenberg!
Wonder what they were thinking of with this installation? Must have saved all of four pence worth of tube...
Part L1 requires you to zone into sleeping and living areas with independent temperature control (and timing control above a certain size). Although this is usually done on a per room basis with TRVs, I believe this is not strictly necessary.
If so, and the pipe runs you have make this divide (i.e. 2 runs do bedrooms and 2 runs do living space), you could convert these single pipe convection runs into single pipe pumped circulation runs by blocking the bypasses and lockshielding the rad valves open.
Then, run living spaces off one zone valve and sleeping zones off another using S-Plan-Plus. Better still, run each pipe as a separate zone and stick a programmable stat in the primary room of each.
This way you get subzoned control and a fully pumped primary circuit. You might be able to do a hybrid system by repiping the 3 rad circuit, for example, but leaving the other runs.
Christian.
| > Actually I have *four* single pipe runs, the maximum number of | > rads on a pipe is three, two with two rads and one with one rad. | > The two with two rads are the main downstairs ones, the others | > upstairs will be in another zone which will be rarely used. |=20 | Part L1 requires you to zone into sleeping and living areas with = independent | temperature control (and timing control above a certain size). Although= this | is usually done on a per room basis with TRVs, I believe this is not | strictly necessary.
I will do this anyway because otherwise upstairs gets too hot in spring and autumn. =20
| If so, and the pipe runs you have make this divide (i.e. 2 runs do = bedrooms | and 2 runs do living space), you could convert these single pipe = convection | runs into single pipe pumped circulation runs by blocking the bypasses = and | lockshielding the rad valves open.
I will put TRVs on all radiators, bar one, probably a towel rail, and have all circuits pumped. The convection option was never used in 25 years, only tested. =20 I intend to have the radiators off for decrudding anyway. =20 | Then, run living spaces off one zone valve and sleeping zones off = another | using S-Plan-Plus. Better still, run each pipe as a separate zone and = stick | a programmable stat in the primary room of each.
???? Google does not give anything on "S-Plan-Plus"
I think I have the circuits organised Downstairs on the boiler controls and upstairs on a separate timer, only operating in winter when the boiler is operating.
--=20 Dave Fawthrop
17,000 free e-books at Project Gutenberg!
Unless I have misunderstood what you are saying, your current system has convection flow into the radiator. The main single loop is pumped, but the rads themselves are convection circulated from the pipe.
My proposed solution means that water is pumped through the rads without convection, but precludes the use of TRVs, as the closing of a TRV would close off the entire zone. However, the fact that you appear to have 4 different single pipe systems means that a maximum of 3 rads would be tied together. If the radiator locations are suitable, then running these as a number of series pumped circuits with no convection at all would meet Part L.
It is a term for S-Plan with more than 2 zones. No special magic involved. S-Plan is fundamentally extensible.
Stick a programmable thermostat in each zone. Old style programmers are old hat.
Christian.
This was the standard way of doing single pipe circuits.
I can see that a single pipe circuit can save on materials, but once you go to several in a house what is the point?
Same reason.
Single pipe system also looks much neater in cases where the pipework is visible -- that was also a significant factor in using it at the time.
Ok. Hadn't thought of that one.
| In article , | Andrew Gabriel wrote: | > > I can see that a single pipe circuit can save on materials, but = once | > > you go to several in a house what is the point? |=20 | > Same reason. |=20 | > Single pipe system also looks much neater in cases where the | > pipework is visible -- that was also a significant factor in | > using it at the time. |=20 | Ok. Hadn't thought of that one.
I actually installed it myself after the "winter of discontent" when the electricity went off on a rota system, so that I could gravity feed if necessary. Never used gravity feed in anger, so I am ditching the system.=20
--=20 Dave Fawthrop
17,000 free e-books at Project Gutenberg!| In article , | Andrew Gabriel wrote: | > > I can see that a single pipe circuit can save on materials, but once | > > you go to several in a house what is the point? | | > Same reason. | | > Single pipe system also looks much neater in cases where the | > pipework is visible -- that was also a significant factor in | > using it at the time. | | Ok. Hadn't thought of that one.
| I actually installed it myself after the "winter of discontent"
The so-called winter of dicontent was 1978/1979. Power went off under Ted Heath in the early 1970s.
| when the electricity went off on a | rota system, so that I could gravity | feed if necessary. Never used gravity | feed in anger, so I am ditching the system.
You need power to operate the system anyway. So, designing it for gravity operation is futile, unless you have a sold fuel boiler available.
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