Do I have a manifold hidden somewhere?

nickpowell77 · 24 May 2014

Hi,

Ever since I moved into my current house 3 years ago I have had problems with a number of radiators heating up to a good temperature. I have played around with the balancing and have made some marginal improvements.

I have tested my pump and it's working fine.

My boiler in in the garage connected to the house and I can see the pump and the pipe running 15m down the garage before disappearing into the ceiling space.

My worry is that I can't see a manifold in the garage and that all of my radiators may be extensions one rad after the other. Is there a way I can tell if this is the case without tearing up the whole of my upstairs?

Thanks

ALCPlumbing · 24 May 2014

How many radiators do you have? Is there more than one room thermostat? Is there only one timer/programmer for your heating?

ALEC1 · 24 May 2014

quite possibly you have a single pipe system, an experienced technician will be able to tell at heat up, and by closing the radiators and monitoring boiler behaviour.

Are you sure the pipe is 15mm..

ALCPlumbing · 24 May 2014

ALEC1 said:
quite possibly you have a single pipe system, an experienced technician will be able to tell at heat up, and by closing the radiators and monitoring boiler behaviour.

Are you sure the pipe is 15mm..

I think he meant the pipe run is 15m as opposed to pipe diameter being 15mm. At least that was how I read it. You could be right about the one pipe system. I was wondering if there's a hidden zone valve that's not opening which was why asked how many room stats, etc.

I hate one pipe systems.

nickpowell77 · 24 May 2014

Thanks all for the quick replies

Yes, sorry, I meant 15ft of pipe run as opposed to 15mm or 15m - even worse hey

We only have one room thermostat and 15 radiators.

I have a Worcester Bosch Greenstar 30CDi Boiler

Some of the radiators, which I'm sure are at the end of the run only get slightly warm. If I turn the other rads off they get boiling hot.

If I have a one pipe system, does that mean I need to have it converted to a manifold or are there other options like a more powerful pump?

Thanks, Nick

simond · 24 May 2014

It's not easy testing the pump, so I'd be interested how you did that.

Poor flow rate to some radiators is common in domestic houses, particularly those which have been extended.

Reason being, the extended areas are usually merely tacked onto the existing pipework and the pressure resistance of the small bore pipe in this location prevents significant amounts of water getting to those rads further afield.

My suggestion would be to shut off all the rads that do get warm, then open them half a turn.

If the house hasn't been extended, check the system is full of water.

Incidentally, unless your house pipework dates from the early 1960s or before, there is little chance of it being a one pipe. These are marginally less efficient than two pipe but perfectly serviceable, we are fitting new plant to them in listed buildings all the time.

In a two pipe system the radiators are all plumbed in parallel, rather than in series. You would only see two pipes leave the airing cupboard for the radiators on a two pipe (ie: modern) system.

nickpowell77 · 24 May 2014

Hi Simon - it's a British Gas pump and on these forums I read that if you take the front off the pump and can stop it with a screwdriver then the pump is not performing. I wasn't able to stop it.

Our house has been converted / extended at least 5 times before we moved in 3 yrs ago, which makes me think they have added on and on to the existing system. The house was built in 1964

The pipes from the boiler split with a Honeywell switch, one branch goes to the Megaflow in the airing cupboard and the other down the garage 15ft and into the ceiling. This just happens to be where the hottest rad in the house is

The reason for my questions is because I'm about to do some major renovation to the ground floor of my house, which will include underfloor heating and I wanted to have clarity on my existing problem before I add any further complications.

Thanks, Nick

simond · 24 May 2014

The pump screw only tells you it is turning, the impeller could still be almost totally blocked.

But by the sound of it, you need some new pipework.

Typical situation, builder tenders for house extension and gets job done in simplest easiest cheapest way.

Winter comes, customer notices new rads are last to warm up and are half the temperature of the existing ones.

When you get the underfloor alterations, might be sensible to get in a boiler specialist rather than use the builder's team for the heating, or you will be back to sq 1.

nickpowell77 · 24 May 2014

Hi Simon - thanks for the advice mate - I see you are also in Surrey. I'm in Send (GU23). Would you be interested in coming around to have a look at the house, so I know what I need to get done. More than happy to pay you for your time.

Cheers, Nick

Richardthe3rd · 24 May 2014

With a 15 radiator system Nick, it would be wise to check the main pipe sizes in your garage. The pipe diameter is critical for correct circulation to your radiators.
HTH

nickpowell77 · 26 May 2014

Thanks - the pipe sized seem to be 15mm

Gasguru · 26 May 2014

You may find the pipework is undersized but the majority of installers do not appreciate that modern boilers eg. the Greenstar CDi/Vaillants have very restrictive heat exchangers, so much so that standard domestic 5 and 6 meter head pumps are insufficient. Google index circuits, go onto the Worcester site and check out the technical bulletin regarding the CDI head loss. You can then determine whether it's a pump issue.

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Do I have a manifold hidden somewhere?

ALEC1

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