Dissapointing new HE Condensating boiler

[Jules]

Hello,

I decided to replace my 30+ year old Floor standing Potterden (SP) boiler with a new boiler. I was pursuaded by a rather dodgy plumber to install a Valliant High Efficiency Condensating Boiler (Eco pro)

I am pretty dissapointing with the results for a number of reasons: a) The system takes longer to warm up the house. (My previous boiler was a basic 60 BTU) and I discover that this plumber installed an 18Kw Boiler to drive 9 radiators in a semi detached house ! It seems to take longer to warm the house up, and does not reach the desired 18 degrees temperature, when outside temperature is sub zero. b) The boiler is noisy, I think its the fan, rather than the pump. I can hear a constant humm in neighbouring rooms. Different humming noises when igniting with a flame indicator, but when no Flame indicator is shown the Boiler seems to be churning around. (The plumber did flush and clean the system through with acid based cleaners several times.) c) The outside condensating pipe always seems to be dripping water, so get a small pool every day.

All in all pretty dissapointing. I wish I had opted to keep the old boiler, or replace with a traditional boiler.

Does anyone else have similiar experience with these new boilers, or any advice on how to improve the heating output, and reduce the fan hum. I cannot afford another boiler.

Jules

[Simon Stroud]

Hi,

Can't comment on a) and b) for this particular boiler but for c) the condensate drain should be dripping water - that's the whole point - and it should be plumbed into a suitable drain, not just left dripping somewhere outside! Sounds like your plumber really was "rather dodgy".

I can't think of any reason why the pump or fan would be running constantly unless it hasn't been properly wired up. I suppose the pump could run continuously under some kind of not-wired-up-correctly condition. It probably would have some kind of "run on" action so the pump continues for a while after burning ends, but not constantly. You would get a "different humming" when the burner is on because the fan would be running then, in addition to the pump.

Regarding the boiler capacity - if you used to have a 60000 BTU/hr boiler then the 18kW is similar (multiply Watts by 3.41 to get the BTU/hr). BUT it's likely that your radiators were sized for the old system running at old-fashioned flow/return temperatures. As the condensing boiler will generally be running with a lower flow and especially return temperature (that's the whole point) the average flow/return temperature will be lower and the heat output of the radiators will be correspondingly less. Therefore if the radiators weren't a bit oversized to start with then they will tend to be a bit wimpy with the condensing boiler. You may be able to adjust (i.e. increase) the flow temperature with some setting on your boiler. BUT if you increase it too much then you may not get proper condensing action if the return temperature is also too high (above I think 56 deg C).

My boiler (Eco Hometec condensing combi) has an outside temperature sensor and adjusts the flow temperature to be higher when colder outside, therefore beefing up the radiator output when needed, and adjusts the burner output and pump speed to ensure that the return temperature is always in the condensing range. Does your Vaillant have a similar action?

Regards, Simon.

[Ed Sirett]

a) What capacity was the old boiler? - 18kW is probably about right for a selection of 9 radiators. It may be that the old radiators had to be run quite hot to get the house warm enough? In which case turning the old boiler up high should fix the problem or adding more powerful radiators.

b) Whatever modern boiler had been fitted there would have been a lot of noise in comparison to the old unit (unless it kettled). There may scope for playing with the pump speed, or building a cupboard around the boiler.

c) The condensate drain should go to a gully or soakaway it should not have been permanently left to drip as a nuissance. I'm suyre the installation manual will have something to say on the matter.

[Pete C]

Hi,

Try balancing the system (see FAQ) and check there is a set back thermostat fitted, and if so check it is set up properly.

Splitting the system into two zones may be of benefit too, it depends how it's used. Should be lots of info on this from past postings via Google Groups.

cheers, Pete.

[Jim Alexander]

The other replies are all about right, I will add that Section 3.3 of the manual the dodgy installer definately left with you mentions the temperature setting issue and Section 10.3 describes the condensate drain issue. Unfortunately retrofitted condensing boilers don't guarantee all the condensing savings as many about to suffer compulsory condensing replacement will find out. However noises apart IMHO you could have had a worse boiler.

You didn't mention any problems with the DHW?

Jim A

[Jules]

Thanks for the replies.

Actually my dodgy plumber didn't leave a manual/user guide behind. I had to download one from the web !

The Description of the controls to the User are not very cleaer in section 3.3. It suggests it is only hot water supply, and does not express any issues with setting it to the max i.e. 80 degrees. (Even though I read form the web, that condensating boilers need to run at lower temperatures for efficiency) I am finding thta I set it to 80 degrees in very cold weather, and back to 65 degrees in moderate wheather for better efficiency.

The manual describes 'Modulating output' but does not really define what this means. This section 3.3 also states that the EcoMax pro, is a fan flue appliance, and operation of the fan can still be heard when the boiler is running and for a short time after it has stopped. So I think my questiosn relate, to why is the fan running for so long, when there is no flame signal. And why do the fans have to be so load. (Its new, and I was under the impression that Vaillant where good boilers.)

DHW - I presume you mean hot water. The same dodgy plumber fitted the Hot water thrmostat on the return pipe, a few feet from the boiler, and the rest of the hot plumbing. I have to set this themo rather high 35 degrees, to get the hot water to to control demand to the cylinder, a couple of rooms away. Seems OK so far. (Have to wait for summer to see if operate without CH demand)

As I said a real dodgy plumber fro yellow pages. Installation of new bolier, with a sealed system fittings and several system clean throughs cost me £2500. So I am not a happy bunny.

Ho hummm (and I am getting a lot of humm from this boiler !)

[Ed Sirett]

That's actually in breach of the regs which are law. Don't suppose he filled in the Benchmark log book. (4 sides of an A5 sized card coloured light blue).

I would appear that you had an existing system that was designed right on the limit w.r.t. the radiator sizing. As and when opportunity arises you should upgrade the radiators especially in parts of the house that 'always cold'. A condensing boiler will do a better job even at 80C than a conventional one.

This section 3.3 also states that the EcoMax pro, is

One person's loud is another's quiet. Call out Vaillant under warranty the guy who comes will be familiar with the noise made by typical units and will do something about it if there is a real problem (there could just be one). Otherwise look to building a cupboard around it. It may be that there is a resonance or rattle occurring.

I'm not clear what you have. The demand for DHW should come from the cylinder stat about 1/4-1/3 up the cylinder.

That's pushing a BG price for a less than middle of the road job. It's 'operatives' like this guy that enable BG to have a market.

_All_ modern boilers make fan noises. See earlier comments.