Heating System Problems - Potterton Profile - Rads not hot

[turbodeas]

Hi all,

I'm new here, and after browsing the forum a little it seems there's a whole lot of expertise here! I'm having a bit of a central heating nightmare at the moment, first I'll describe the system a little....

I live in a 2 bed duplex (2 floors) flat, which is a strange design converted from a huge old Victorian house, and as such is very spread out.

I have a Potterton Profile (I think it's a 30 or 40e....Doesn't say anywhere on it) boiler, which is connected to an open vented system with gravity fed hot water. There is no electric valve anywhere in sight.
The boiler is situated in a compartment upstairs, and the expansion tank is directly above the boiler (about 12 inches above!). The hot water cylinder is downstairs in the bathroom airing cupboard, and has no stat that I can see.
Upstairs there are 2 rads, downstairs there are 7. It's a landlord owned property, and before I moved in all the pipework was switched from narrow bore to wide bore (about 1.5cm cross section I think..) pipes by a non-corgi Polish plumber.
The pipes go under the floorboards from the boiler, and travel downstairs via the airing cupboard, then go under the floorboards into the unheated basement to travel to all the rads.

My problem is that the rads just don't get hot enough! I have the heating programmed to be on for about 8 hours a day, and last week I had a gas bill, £200 for 2 months. This seems highly excessive, so I instantly thought the system must be loosing a huge amount of efficiency somewhere....
British Gas came round to have a look at it all, and the bloke was horrified at the design of the system. He told me the expansion tank is not high enough to provide enough pressure for a system that size, and it's just sucking air into the system. He also told me that the pipes that travel downstairs to the 7 rads downstairs should be 1 inch wide bore pipes, whereas in fact they are the same as the pipes feeding each radiator. He said simply fitting a more powerful pump wouldn't solve the problem, it would just suck more and more air into the system.
He reccomended having it converted to a sealed system, and said we would probably get away with the small(er) bore pipes feeding the downstairs rads if it was sealed.
So, what do people think of this reccomendation? Is my boiler compatible with a sealed system? I have a plumber coming round tommorrow (corgi registered according to the landlord) and I just want a second opinion before I say yes to any work!
Also, how easy would it be to fix a 3 way valve and stat to the hot water tank? Is that a big/expensive job to do at the same time? I'd really like to try and lower my bills - initial thoughts are that the flat just isn't getting up to the roomstat temperature due to poor plumbing, but the boiler is going flat out!

Many thanks,

Chris.

 

[gas4you]

Says it all if a polish has worked on it

Changing to a sealed system will (should) eliminate any problems with sucking in air, but other than that won't make much difference to the lower rads getting hot.

Stop paying your rent until the landlord gets it sorted properly

 

[turbodeas]

No? The bloke from British Gas seemed to think that converting to a sealed system would result in much greater pressure going to the downstairs rads, squeezing it through the thinner pipes.

It'll be a bit of a big job to change the thin pipes to fat ones I think...But yeah, I might hold back on this months rent until it's sorted and i'm getting the roomstat clicking at 20 degrees....It never usually makes it up that far in my flat, hence the boiler going all the time. Do you think that's why I had such a huge bill?

Cheers,

Chris.

 

[turbodeas]

Right,

Just had the plumber who my landlord contracted out to do the work come and have a look. He was a nice fella with all the relevant accreditations.

He had a more in depth poke round at the system and discovered the boiler was mounted on two metal bars hanging off the wall, and that the compartment vents were a couple of holes drilled through to the outside! Behind these metal bars it was just a load of expanding foam keeping the flue in place...

He also went down into the basement beneath my ground floor flat and found that the dodgy Polish "plumber" had installed a second pump in addition to the one in the boiler cupboard!

Looks like BG were right that the pipes to the downstairs rads are too small, he told me that they're 15mm and they're feeding 7 rads, which isn't really on.

As it's a landlord job no money was talked about - does anyone have an idea how much a job like this will cost? Just out of interest...

Convert to sealed system, new cylinder stat, new valve, new pipework to all the downstairs rads...

Cheers,

Chris.

 

[Agile]

We would charge about £136 to convert to a sealed system at the F&E tank location

Fitting full controls would be £240 less whatever controls the system already has.

Certainly 15 mm pipework to seven rads is grossly undersized. We would probably charge about £14 per metre of new 22 mm pipework but that might be higher if some of it is less accessible.

There can be other more lateral ways of dealing like a second 15 mm feeding the opposite end of the rad system if thats easier to fit.

Ideally it needs 22 mm to the centre of the 15 mm distribution or often 22 mm to feed to the junction between upstairs and downstairs in 15 mm.

Tony

 

[turbodeas]

Thanks for that Tony, interesting to hear. I think either way the landlord isn't going to be particularly happy! As the tenant, all I want is a decent heating system that doesn't cost me the earth to run.

Does anyone know if my boiler, a Potterton Profile (either 40e or 50e) is a reasonably efficient machine?

Chris.

 

[Agile]

Its slightly lower than the best non condensing boiler as its a cast iron heat exchanger.

Perhaps about 75% efficient.

The latest condensing boilers are over 90%.

Not terribly important to a tenant though.

Interesting that an energy efficiency certificate was required for all new lets after october 2008 but I have not heard of any being done. I suppose another bit of legislation that is not being enforced!

Tony.

 

[turbodeas]

Tony,

Thanks for the information, interesting to read.

The original plumber can't start the job until the end of next week at a push, so the landlord has rang his other plumber mate...

He came and did a site survey today, and decided it'd be best putting a condensing combi in instead of converting the current system - he mentioned something about the tank not being able to accommodate a thermostat.

The landlord (who was with him at the time) said he had a source of cheap combis...Based on the information I gave in the first post (9 rads, two large over 1.5m long, and HW with electric shower) what size combi do you think would be neccessary to heat the flat efficiently? I'm just worried the landlord's "cheap combi" will be something far too small for the job....

Cheers again everyone,

Chris.

 

[Agile]

Tony,

The landlord (who was with him at the time) said he had a source of cheap combis..

Chris.

Expect a Turkish made Heatline Vizo then !