Running a combination boiler without central heating connected?

Aug 30, 2005 7 Replies

Can one temporarily short out, with a pipe, the central heating circuit of a combination boiler, so that I can get the DHW working first, and do the central heating later? Clearly in summer the hot water will work OK with the central heating not working.



The cylinder has to go first before I can fit the combination boiler, can be fitted.


At a guess I would think that most would cope fine as long as that pipe used to short the circuit had a radiator in it. I would think that nasty things could happen if it is just a short bit of pipe - it wouldn't take much for the boiler firing the heating circuit up to lead to superheated water ( > 100C).

What boiler is it?

Check the instructions. If the boiler already has a automatic bypass, then it should be ok to isolate the radiator circuit. Otherwise just install the bypass across flow/return and isolate the circuit below it.

| At a guess I would think that most would cope fine as long as that pipe | used to short the circuit had a radiator in it. I would think that | nasty things could happen if it is just a short bit of pipe - it | wouldn't take much for the boiler firing the heating circuit up to lead | to superheated water ( > 100C). | | What boiler is it?

Not chosen it yet.

I'd check with the manufacturers, (of course).

To be on the safe side a couple of temporary connection to a temporary radiator should probably do the trick.

I'd be careful if I were you - I gave an almost identical answer and got right royally jumped on for giving an answer that was not 100% copper bottomed guaranteed to be correct.

I have run a (Vaillant) combi without the rads for a day, just using the flow/return isolators shutoff. This allowed me to get the customer's hot water back on at the end of the first day's work.

I was very careful to make sure that the air was well out of the boiler, it was considerable noiser as there was no where for the small air bubble to escape to.

If anyone does this and they damage their nice new boiler then it's nothing to do with me.

| On Thu, 01 Sep 2005 09:14:38 -0700, Matt Beard wrote: | | > | > Ed Sirett wrote: | >> On Tue, 30 Aug 2005 01:32:45 -0700, Matt Beard wrote: | >>

| >> > At a guess I would think that most would cope fine as long as that pipe | >> > used to short the circuit had a radiator in it. I would think that | >> > nasty things could happen if it is just a short bit of pipe - it | >> > wouldn't take much for the boiler firing the heating circuit up to lead | >> > to superheated water ( > 100C). | >> >

| >> > What boiler is it? | >>

| >> I'd check with the manufacturers, (of course). | >>

| >> To be on the safe side a couple of | >> temporary connections to a temporary radiator should probably do the | >> trick. | >>

| >>

| > I'd be careful if I were you - I gave an almost identical answer and got | > right royally jumped on for giving an answer that was not 100% copper | > bottomed guaranteed to be correct. | | I have run a (Vaillant) combi without the rads for a day, just using the | flow/return isolators shutoff. This allowed me to get the customer's hot | water back on at the end of the first day's work. | | I was very careful to make sure that the air was well out of the boiler, | it was considerable noiser as there was no where for the small air | bubble to escape to. | | If anyone does this and they damage their nice new boiler then it's | nothing to do with me.

OK OK. Plans have changed. I am re-routing the central heating pipes first, so they can be just connected to the new boiler when it arrives.

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