Cool Radiators Downstairs

[Riz]

Hi guys and girls,

I'm a first time poster so apologies if my knowledge comes across a tad green. My system is a standard boiler system (i.e. not a combi).

I've got an issue where my radiators downstairs are cooler than the ones upstairs. The upstairs ones are nice and hot but the downstairs are luke-warm.

I've had my local plumber out and he's flushed the system using his special flushing equipment.

I've also noticed that there's a bit of noise coming from the heating system, which I think emanates from the pump. However I mentioned this to my plumber and he thinks the pump is fine.

There's also one radiator that's closest to the hot water tank that has to be bled regularly (1-2 times a week). I don't know if this is relevant or not.

The house is struggling to get above 16C, even when having the heating on for a week. The house is fairly well insulated (the snow didn't vanish off the roof recently).

Can anyone offer any advice as to why my downstairs radiators are comparatively cold?

 

[54ab]

possible pump on way out, heat rises, pumping but not fully , I would replace pump,

 

[Bernie2]

Agree with 54ab,

Its first stop, seems to be classical pump problem, air lock or valve shut.

 

[Riz]

Thanks very much for the quick response.

I'll give it a go and let you know how it goes.



BTW, can anyone suggest a good brand?

Also my friend says that it might be that the rads upstairs need to turned off, then later re-opened to half way. Could that sort it?

 

[migoplumber]

grundfoss pumps are the best. if you want to splash out go for the electronic a rated models.

 

[Deleted member 2053]

Wilo pumps are also very good and a bit cheaper than Grundfoss, who from my recent experiences seem to be losing their market edge.

 

[Riz]

Found the Grundfos Alpha2 15/50 for £75 +VAT so ordered that as it's not much dearer than a standard pump.

My plumber's going to install it as soon as it comes in so will let you know how it goes.

Thanks!

 

[Riz]

Re: Cool Radiators Downstairs - The Problem Continues!

Hi,

Thanks for the advice so far guys.

I've replaced the pump with a Grunfoss Alpha 2. Seems to be working nicely but unfortunately the problem still persists!

I'm beginning to wonder if it's got something to do with my Potterton Suprema boiler or the Danfoss TP75RF controller?

The boiler comes on for about a minute and then stops (flashing green light). After about 3 minutes, it starts up again (for another minute). Occasionally it looks like the Alpha 2 resets itself as all the lights come on, and then it settles back down to the right setting.

If it helps I've uploaded a couple of pictures of my set-up as well as a short movie of the problem to my MobileMe account: MobileMe Gallery

Any ideas greatly appreciated.

Thanks.

 

[dontknowitall]

Possibly a silly question, but presumably you put the pump on the correct way round? In case you're unsure, there's an arrow imprinted in it's body indicating the direction of water flow.

 

[Riz]

Thanks for your response. Yes pump definitely the right way round.

I've done some more testing with Danfoss, the control unit manufacturers. Basically when boiling water for hot water, it seems to work fine...burns for about 7-8 minutes before pausing and then starting after minute. However when boiling water for central heating it doesn't seem to work.

I've noticed a wheezing coming from the boiler just before it stops burning when doing the central heating (it doesn't do it for the hot water).

I think conclusions tend to be the boiler as being an issue, but I'm wondering where the wheezing is coming from?

 

[BoilerPro]

To be honest, I would have gone with balancing as the first and cheapest option. It costs absolutely nothing and can be ruled out very quickly. Your now down the price of a new pump and plumbers labour for what would appear to have been a perfectly good pump already. Before you spend any more money on it try the following:

Turn off water to hot water cylinder. Turn off all rads upstairs. Ensure room stats/trvs are set to high downstairs. Leave for a while and see if rads heat up. Once they do, turn back on rads upstairs and re-open cyclinder no more than one turn. It may take a little extra time to heat water for showers/baths etc. but will give you heat downstairs.

Also, you didn't mention whether you've always had this problem downstairs or if it is a recent problem. If it has always been this way it is possible that the pump is underspeced for the house. Don't assume the plumber who refit the new one bothered to check whether it was right for the job. If balancing doesn't work let us know the size of your system, e.g. number of rads, size of house etc.

Kevin

 

[Riz]

Hi Kevin and thanks for your input.

I should have mentioned (sorry) that I've already tried balancing the radiators.

The pump has been fine for the last 7 years and I've changed it to a Alpha2 15/50 which is what the previous spec was. During that process I had to drain the system.

I've got a 3 bed semi, with 4 radiators upstairs and 4 downstairs.

Hope that helps give more insight.

 

[LeakyJim]

Hi everyone.
I think I would check the three port valve. Boiler works ok for HW but not for heating, classic sign.

 

[Riz]

Hi Jim and thanks for your advice.

Would that also explain why the boiler cuts out with the central heating but not with the hot water?

 

[plumber]

defintley sounds like three port valve has gone