Posted by: @samiebon1

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Had a Vaillant 5kW installed last week and upstairs is getting up to temp ok, but all the downstairs radiators are luke warm at best.

I've tried balancing but no such luck. They are column rads, but I've got columns upstairs which are getting warm.

A couple of thoughts/questions - could this be resolved by topping up the system pressure more (analogue dial says 1.5, digital says 1.2); could I modify the remaining feed head setting (currently 900); or... Something else?

Also, my DHW doesn't seem to be getting up to temp. It has a 3 hour period over night to charge and I've set the offset to 15K which I thought would be enough. Any suggestions?

 

Thanks all!

@samiebon1 

You had it installed only last week?  I would suggest that you need to do nothing and get the installer back pronto!

@morgan I will be getting them back, but wanting to understand/foresee issues so I can challenge the installer when they return.

@samiebon1 Isn’t it a sad situation when we feel we must be ‘armed’ with an argument and / or a prepared report to hand over to the installer on their return when they have failed to carry out a good install? Perhaps the good installer would not have carried out a botched job in the first place but, wouldn’t it refreshing if the installer returned and said “Oh I am sorry we made such a mess of this job, we will put it right immediately and I am so sorry to have caused you this inconvenience in the first place!”? —— Yes, I live in cloud cuckoo land I know! 😉 Regrets, Toodles.

@samiebon1 

I don't have a Vaillant so unable to assist with specifics, sorry.

Posted by: @samiebon1

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Had a Vaillant 5kW installed last week and upstairs is getting up to temp ok, but all the downstairs radiators are luke warm at best.

I've tried balancing but no such luck. They are column rads, but I've got columns upstairs which are getting warm.

A couple of thoughts/questions - could this be resolved by topping up the system pressure more (analogue dial says 1.5, digital says 1.2); could I modify the remaining feed head setting (currently 900); or... Something else?

Also, my DHW doesn't seem to be getting up to temp. It has a 3 hour period over night to charge and I've set the offset to 15K which I thought would be enough. Any suggestions?

 

Thanks all!

Something is wrong with the plumbing for sure.  Have the downstairs rads been bled?  Are they on a separate primary or do they share a primary with the upstairs?

Unless your house is very tall 1.2 bar should suffice

Re the DHW what tank do you have and how much hot water do you use.  Also what do you mean by 'up to temperature'  5kW is actually quite small if you use a lot of DHW.  So if, for example, you are trying to heat 300l from cold (10) to 50, its going to take 3 hours

As @toodles says, at this stage its definitely something your installer should fix but I'm like you and prefer to be a step ahead!

@jamespa As far as I can tell they have been bled (water comes out when I bleed them). Theyre on the same primary as upstairs - 22mm copper running along upstairs, then down. Could anything be done with the 'remaining feed head' setting or is that a non starter?

Its a 150L 'UK Cylinders' heat pump tank. Its got a 3 hour window to heat in from ~36 to 48 deg so shouldn't take that long.

@samiebon1 Sounds as though the output from the heatpump is being throttled back in some way. If the system was sized appropriately, then all the radiators should be supplied with sufficient heat to bring them to temperature readily. There may be a blockage / restriction in the flow before the pipework descends to the ground floor radiators. Possibly an air lock; have you information on the consumption and how long the heat pump is running and idling? It is worth checking up on these points. Regards, Toodles.

Posted by: @samiebon1

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As far as I can tell they have been bled (water comes out when I bleed them). Theyre on the same primary as upstairs - 22mm copper running along upstairs, then down. Could anything be done with the 'remaining feed head' setting or is that a non starter?

OK so downstairs is 'after' upstairs.  You may have to throttle down the LSVs upstairs, increase the pump head if thats an option, and open up (if you can) the LSVs downstairs.  As @toodles says there could be an air lock, Vaillant has  a 'purge' function in the installer menu which my installer said was supposed to deal with this (presumably by whacking the water pump up to max).

Posted by: @samiebon1

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Its a 150L 'UK Cylinders' heat pump tank. Its got a 3 hour window to heat in from ~36 to 48 deg so shouldn't take that long.

No it shouldn't, nowhere near!

Here is my 200l tank reheating today from/to about the same temperature.  22mm diameter feeds teeing off the 28mm primaries from the heat pump.  I have a 7kW Vaillant.  Something definitely wrong with yours, can you tell what temp the pipes are to and at the DHW tank and what diameter are they?  I suppose its not possible that the installer has fitted a normal 3 way valve instead of a diverter valve (you would know as your heating would be on simultaneously with your DHW) 

Posted by: @jamespa

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I suppose its not possible that the installer has fitted a normal 3 way valve instead of a diverter valve (you would know as your heating would be on simultaneously with your DHW).

That happened with my installation. Whoever had been sent to the plumbing suppliers to buy various parts got the wrong type of valve. Once the system was running I noticed that one of the upstairs radiators was getting warm when the DHW was being heated. That was convection flow as the circulating pump wasn't running.

I think the pipe work and 3 way valve is ok from what I can see/read up. I had wondered if it's the settings - I have weather adaptation on so at the moment it's ~40deg flow, and my DHW offset is 15k (was 10k). Would this 55deg flow around the cylinder be enough to get up to target 48deg water temp?

The installer has arranged to come Monday so at least it's pencilled in!

Posted by: @samiebon1

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I think the pipe work and 3 way valve is ok from what I can see/read up. I had wondered if it's the settings - I have weather adaptation on so at the moment it's ~40deg flow, and my DHW offset is 15k (was 10k). Would this 55deg flow around the cylinder be enough to get up to target 48deg water temp?

 

The installer has arranged to come Monday so at least it's pencilled in!

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DHW flow temp is completely separate to space heating flow temp.  The offset is added to the target DHW temp to get the FT for DHW.  15K should be ample in principle although the cylinder supplied has a relatively small area coil (1.6 sq m) compared to 3 sq m often recommended.  That said so does the Vaillant 150l cylinder!  Feels to me like something is wrong, suggest you check the pipe temps near the DHW cylinder if you can!