A few questions to plumbing experts

[fresher]

Hello everyone,

I am Peter, new here, nice to meet you all experts!

My house has insulated brick cavity wall, old double glazed aluminium windows which sit on wooden frames, open vented heating system, boiler the Worchester Green star 15Ri, 8 radiators in house.

1. Recently I had 7 radiators changed in my house (3 bed) as old ones did not produce enough heat in my opinion.

All radiators fitted upstairs in bedrooms are doing great job, the problem is in my dining room/livingroom (one open space) of which dimensions are W3.9m- L7m-H2.3m, window area 7.6msq, it just takes very long to heat up. Normally I have to wait around one hour for temperature to raise by 1 degree, is that normal??
The radiators: one under window horizontal designer rad has 1537W and one on the other end of room has 1550W it is a convector radiator, both radiators are very hot but the horizontal radiator bottom is cooler than pipping hot top. My question is did I purchase to small radiators for the space?? All BTU calculators were recommending around 2800W for this space, ones I have totals up to just over 3100W. My boiler is set to around 85%.

2. I have an open vented system, I have asked my plumber to add Fernox F1 to new radiators and he poured two bottles in to expansion tank in the loft, would fernox reach all radiators from there? Should it be added in to the bathroom rads instead for example?

3. My pump next to hot water cylinder is GRUNDFOS Type 15-50 130, I have noticed that it is set to speed no 3 (the highest) I have heard that it shouldn't be on the highest speed as it can lead to radiators corrosion, is that true? this pump always been on setting 3 since I moved in 2 years ago, should it be set no number 2 to avoid radiators damage?

4. My plumber said that it is normal that the bottom of horizontal rad is cooler than top, is he correct? The top is pipping hot, the bottom just warm.

I would appreciate all help and advises.

Peter

 

[ShaunCorbs]

what size is the piping to the problem rads? 10mm or 15mm

 

[fresher]

Hi Shaun, pipes are 15mm.

 

[ShaunCorbs]

Hi Shaun, pipes are 15mm.

thats good, and vertical rads arnt the best for heating a room at the best of times

question 3

I have heard that it shouldn't be on the highest speed as it can lead to radiators corrosion

no this is false doesnt matter what speed corrosion will always happen thats why we as inhibitor to help

and question 4 heat rises so the hottest will be at the top and will cool and go into the return

 

[joni os]

Is the ground floor solid or suspended.

 

[fresher]

Thanks Shaun. joni it is solid, house built in 1958. concrete floor with floor panels on it.

 

[joni os]

Ventilation losses, two air changes/hour would account for 1Kw, one third of rads output, so drafts should be eliminated and any open fireplace sealed. Fully open lockshield valves on downstairs rads to ensure flow sufficient to achieve rated output.

 

[snowhead]

What temperature is the room when the heating first comes on?

Which way is the Horizontal rad piped;

Both pipes the same end,?
If so,

Flow in the top, return out the bottom
OR Flow in the bottom, return out the top? (check when the heating first comes on and both pipes are cold)

 

[fresher]

Joni I do have a fireplace, maybe I should block it, so heat can't escape thorough ?
Snowhead temp is normally around 18 degrees, pipes run in the bottom of the rad, flow pipe connected to the right side and return connected to the left side.

 

[joni os]

Continuing the process of elimination. The pump was set to 3 on the old and unsatisfactory heating system and has not been changed. Before spending on larger rads. ensure vanes not partially blocked, and pump is 100%.

 

[jonnyswamp]

Also, stating the obvious, only block the fireplace if it isn't being used, eg gas or solid fuel fire etc don't block it off

 

[fresher]

Joni how to check if vanes are blocked ? Also regarding Fernox question wass it poured in correct place?

 

[joni os]

Need to isolate pump and split body where connected with allen headed screws. Be prepared to catch some water and if isolation valves don't hold a drain down to pump level is required.
Fernox can be sorted by tying up ballcock to F&E tank, draining system at low point into plastic containers until tank empty and refilling F&E tank from containers. If you have to drain down to pump level to service pump this can be part of the process and your inhibitor saved. If pump lower than rads. close rads both ends to minimize drain down.

 

[stevetheplumber]

ive found all designer rads to be optimistic in there output figures if the rads are getting hot and the room isnt heating then the rads are to small closing the fire place may help but you do need to keep some airflow in the form of a small louvred vent unless your going to cap the chimney at the top

 

[stevetheplumber]

i would ignore the vanes being blocked on the pump

 

[joni os]

The output of the rads depend on the average temp between top and bottom and the room temp.75/65 to 20 room temp gives 50 differential. 75/45 gives 40 differential and heat output will be 20% less. Increased flow through the rad will increase average temp and output. The common factor in old and new system is pump, don't ignore it.

 

[fresher]

joni, if I won't do that Fernox won't reach to radiators from that tank under roof ? Is that tank water circulated in radiators ? My plumber said it is.

 

[stevetheplumber]

water in the header is more or less stagnant so you need to drain some out to get the fernox into the system

 

[Welder]

Personally, the first thing id do is get the system properly balanced and i cant believe no one has said that.

Is the system sludged up?

Once the system is both clean and appropriately balanced which will also sortbthe correct pump speed, its at that point you look elsewhere.

 

[jtsplumbing]

1. get boiler checked to see that it is producing enough heat .
2. How old is pump ? could be on speed 3 to try and compensate for age of pump , just because its running doesn't mean it's working fully

 

[1Steven]

Personally, the first thing id do is get the system properly balanced and i cant believe no one has said that.

Is the system sludged up?

Once the system is both clean and appropriately balanced which will also sortbthe correct pump speed, its at that point you look elsewhere.

I was reading through and thinking the same!